diff --git a/packages/graphql/src/schema/initCollections.ts b/packages/graphql/src/schema/initCollections.ts
index 3c8322ece..8c7d51019 100644
--- a/packages/graphql/src/schema/initCollections.ts
+++ b/packages/graphql/src/schema/initCollections.ts
@@ -14,7 +14,7 @@ import {
   GraphQLString,
 } from 'graphql'
 import { buildVersionCollectionFields, flattenTopLevelFields, formatNames, toWords } from 'payload'
-import { fieldAffectsData } from 'payload/shared'
+import { fieldAffectsData, getLoginOptions } from 'payload/shared'
 
 import type { ObjectTypeConfig } from './buildObjectType.js'
 
@@ -442,10 +442,9 @@ export function initCollections({ config, graphqlResult }: InitCollectionsGraphQ
       if (!collectionConfig.auth.disableLocalStrategy) {
         const authArgs = {}
 
-        const canLoginWithEmail =
-          !collectionConfig.auth.loginWithUsername ||
-          collectionConfig.auth.loginWithUsername?.allowEmailLogin
-        const canLoginWithUsername = collectionConfig.auth.loginWithUsername
+        const { canLoginWithEmail, canLoginWithUsername } = getLoginOptions(
+          collectionConfig.auth.loginWithUsername,
+        )
 
         if (canLoginWithEmail) {
           authArgs['email'] = { type: new GraphQLNonNull(GraphQLString) }
diff --git a/packages/next/src/views/Login/LoginForm/index.tsx b/packages/next/src/views/Login/LoginForm/index.tsx
index a1193e0dd..a361b3704 100644
--- a/packages/next/src/views/Login/LoginForm/index.tsx
+++ b/packages/next/src/views/Login/LoginForm/index.tsx
@@ -11,6 +11,7 @@ import type { FormState } from 'payload'
 
 import { Form, FormSubmit, PasswordField, useAuth, useConfig, useTranslation } from '@payloadcms/ui'
 import { formatAdminURL } from '@payloadcms/ui/shared'
+import { getLoginOptions } from 'payload/shared'
 
 import type { LoginFieldProps } from '../LoginField/index.js'
 
@@ -36,9 +37,7 @@ export const LoginForm: React.FC<{
   const collectionConfig = config.collections?.find((collection) => collection?.slug === userSlug)
   const { auth: authOptions } = collectionConfig
   const loginWithUsername = authOptions.loginWithUsername
-  const canLoginWithEmail =
-    !authOptions.loginWithUsername || authOptions.loginWithUsername.allowEmailLogin
-  const canLoginWithUsername = authOptions.loginWithUsername
+  const { canLoginWithEmail, canLoginWithUsername } = getLoginOptions(loginWithUsername)
 
   const [loginType] = React.useState<LoginFieldProps['type']>(() => {
     if (canLoginWithEmail && canLoginWithUsername) {
diff --git a/packages/payload/src/auth/getAuthFields.ts b/packages/payload/src/auth/getAuthFields.ts
index 702d12193..122c43984 100644
--- a/packages/payload/src/auth/getAuthFields.ts
+++ b/packages/payload/src/auth/getAuthFields.ts
@@ -28,6 +28,9 @@ export const getBaseAuthFields = (authConfig: IncomingAuthType): Field[] => {
         if (authConfig.loginWithUsername.requireUsername === false) {
           usernameField.required = false
         }
+        if (authConfig.loginWithUsername.allowEmailLogin === false) {
+          emailField.unique = false
+        }
       }
     }
 
diff --git a/packages/payload/src/auth/getLoginOptions.ts b/packages/payload/src/auth/getLoginOptions.ts
new file mode 100644
index 000000000..4a4fdb6be
--- /dev/null
+++ b/packages/payload/src/auth/getLoginOptions.ts
@@ -0,0 +1,13 @@
+import type { Auth } from './types.js'
+
+export const getLoginOptions = (
+  loginWithUsername: Auth['loginWithUsername'],
+): {
+  canLoginWithEmail: boolean
+  canLoginWithUsername: boolean
+} => {
+  return {
+    canLoginWithEmail: !loginWithUsername || loginWithUsername.allowEmailLogin,
+    canLoginWithUsername: Boolean(loginWithUsername),
+  }
+}
diff --git a/packages/payload/src/auth/operations/forgotPassword.ts b/packages/payload/src/auth/operations/forgotPassword.ts
index 8b6d1b479..082bef0bd 100644
--- a/packages/payload/src/auth/operations/forgotPassword.ts
+++ b/packages/payload/src/auth/operations/forgotPassword.ts
@@ -14,6 +14,7 @@ import { APIError } from '../../errors/index.js'
 import { commitTransaction } from '../../utilities/commitTransaction.js'
 import { initTransaction } from '../../utilities/initTransaction.js'
 import { killTransaction } from '../../utilities/killTransaction.js'
+import { getLoginOptions } from '../getLoginOptions.js'
 
 export type Arguments<TSlug extends CollectionSlug> = {
   collection: Collection
@@ -33,8 +34,7 @@ export const forgotPasswordOperation = async <TSlug extends CollectionSlug>(
   const loginWithUsername = incomingArgs.collection.config.auth.loginWithUsername
   const { data } = incomingArgs
 
-  const canLoginWithUsername = Boolean(loginWithUsername)
-  const canLoginWithEmail = !loginWithUsername || loginWithUsername.allowEmailLogin
+  const { canLoginWithEmail, canLoginWithUsername } = getLoginOptions(loginWithUsername)
 
   const sanitizedEmail =
     (canLoginWithEmail && (incomingArgs.data.email || '').toLowerCase().trim()) || null
diff --git a/packages/payload/src/auth/operations/login.ts b/packages/payload/src/auth/operations/login.ts
index f9c54f913..bbc2c28a9 100644
--- a/packages/payload/src/auth/operations/login.ts
+++ b/packages/payload/src/auth/operations/login.ts
@@ -13,6 +13,7 @@ import { afterRead } from '../../fields/hooks/afterRead/index.js'
 import { killTransaction } from '../../utilities/killTransaction.js'
 import sanitizeInternalFields from '../../utilities/sanitizeInternalFields.js'
 import { getFieldsToSign } from '../getFieldsToSign.js'
+import { getLoginOptions } from '../getLoginOptions.js'
 import isLocked from '../isLocked.js'
 import { jwtSign } from '../jwt.js'
 import { authenticateLocalStrategy } from '../strategies/local/authenticate.js'
@@ -87,8 +88,7 @@ export const loginOperation = async <TSlug extends CollectionSlug>(
         ? data.username.toLowerCase().trim()
         : null
 
-    const canLoginWithUsername = Boolean(loginWithUsername)
-    const canLoginWithEmail = !loginWithUsername || loginWithUsername.allowEmailLogin
+    const { canLoginWithEmail, canLoginWithUsername } = getLoginOptions(loginWithUsername)
 
     // cannot login with email, did not provide username
     if (!canLoginWithEmail && !sanitizedUsername) {
diff --git a/packages/payload/src/auth/operations/unlock.ts b/packages/payload/src/auth/operations/unlock.ts
index f6d331835..a6b6e44ee 100644
--- a/packages/payload/src/auth/operations/unlock.ts
+++ b/packages/payload/src/auth/operations/unlock.ts
@@ -12,6 +12,7 @@ import { commitTransaction } from '../../utilities/commitTransaction.js'
 import { initTransaction } from '../../utilities/initTransaction.js'
 import { killTransaction } from '../../utilities/killTransaction.js'
 import executeAccess from '../executeAccess.js'
+import { getLoginOptions } from '../getLoginOptions.js'
 import { resetLoginAttempts } from '../strategies/local/resetLoginAttempts.js'
 
 export type Arguments<TSlug extends CollectionSlug> = {
@@ -32,8 +33,8 @@ export const unlockOperation = async <TSlug extends CollectionSlug>(
   } = args
 
   const loginWithUsername = collectionConfig.auth.loginWithUsername
-  const canLoginWithUsername = Boolean(loginWithUsername)
-  const canLoginWithEmail = !loginWithUsername || loginWithUsername.allowEmailLogin
+
+  const { canLoginWithEmail, canLoginWithUsername } = getLoginOptions(loginWithUsername)
 
   const sanitizedEmail = canLoginWithEmail && (args.data?.email || '').toLowerCase().trim()
   const sanitizedUsername =
diff --git a/packages/payload/src/auth/strategies/local/register.ts b/packages/payload/src/auth/strategies/local/register.ts
index fede389d3..c4bc266b7 100644
--- a/packages/payload/src/auth/strategies/local/register.ts
+++ b/packages/payload/src/auth/strategies/local/register.ts
@@ -3,6 +3,7 @@ import type { JsonObject, Payload } from '../../../index.js'
 import type { PayloadRequest, SelectType, Where } from '../../../types/index.js'
 
 import { ValidationError } from '../../../errors/index.js'
+import { getLoginOptions } from '../../getLoginOptions.js'
 import { generatePasswordSaltHash } from './generatePasswordSaltHash.js'
 
 type Args = {
@@ -24,9 +25,11 @@ export const registerLocalStrategy = async ({
 }: Args): Promise<Record<string, unknown>> => {
   const loginWithUsername = collection?.auth?.loginWithUsername
 
+  const { canLoginWithEmail, canLoginWithUsername } = getLoginOptions(loginWithUsername)
+
   let whereConstraint: Where
 
-  if (!loginWithUsername) {
+  if (!canLoginWithUsername) {
     whereConstraint = {
       email: {
         equals: doc.email,
@@ -37,7 +40,7 @@ export const registerLocalStrategy = async ({
       or: [],
     }
 
-    if (doc.email) {
+    if (canLoginWithEmail && doc.email) {
       whereConstraint.or?.push({
         email: {
           equals: doc.email,
@@ -67,7 +70,7 @@ export const registerLocalStrategy = async ({
     throw new ValidationError({
       collection: collection.slug,
       errors: [
-        loginWithUsername
+        canLoginWithUsername
           ? {
               message: req.t('error:usernameAlreadyRegistered'),
               path: 'username',
diff --git a/packages/payload/src/exports/shared.ts b/packages/payload/src/exports/shared.ts
index 76ff98576..29f7d6c12 100644
--- a/packages/payload/src/exports/shared.ts
+++ b/packages/payload/src/exports/shared.ts
@@ -5,6 +5,7 @@ export {
   getCookieExpiration,
   parseCookies,
 } from '../auth/cookies.js'
+export { getLoginOptions } from '../auth/getLoginOptions.js'
 export { getFromImportMap } from '../bin/generateImportMap/getFromImportMap.js'
 export { parsePayloadComponent } from '../bin/generateImportMap/parsePayloadComponent.js'
 export { defaults as collectionDefaults } from '../collections/config/defaults.js'