diff --git a/docs/en_US/release_notes_6_15.rst b/docs/en_US/release_notes_6_15.rst
index 22442c5fa..b894b2109 100644
--- a/docs/en_US/release_notes_6_15.rst
+++ b/docs/en_US/release_notes_6_15.rst
@@ -25,4 +25,5 @@ Bug fixes
 *********
 
   | `Issue #5249 <https://github.com/pgadmin-org/pgadmin4/issues/5249>`_ -  Added the ability to display the selected text from the query tool in the find/replace box.
+  | `Issue #5262 <https://github.com/pgadmin-org/pgadmin4/issues/5262>`_ -  Ensure that the user management dialog should not allow the same email addresses with different letter casings when creating users.
   | `Issue #5308 <https://github.com/pgadmin-org/pgadmin4/issues/5308>`_ -  Ensure that the default value for a column should be used if it is made empty.
diff --git a/web/pgadmin/tools/user_management/static/js/UserManagementDialog.jsx b/web/pgadmin/tools/user_management/static/js/UserManagementDialog.jsx
index b0974e01f..b721ced20 100644
--- a/web/pgadmin/tools/user_management/static/js/UserManagementDialog.jsx
+++ b/web/pgadmin/tools/user_management/static/js/UserManagementDialog.jsx
@@ -145,7 +145,7 @@ class UserManagementCollection extends BaseUISchema {
       if (obj.isNew(state) && obj.top?._sessData?.userManagement) {
         for (let i=0; i < obj.top._sessData.userManagement.length; i++) {
           if (obj.top._sessData.userManagement[i]?.id &&
-            obj.top._sessData.userManagement[i].username == state.username &&
+            obj.top._sessData.userManagement[i].username.toLowerCase() == state.username.toLowerCase() &&
             obj.top._sessData.userManagement[i].auth_source == state.auth_source) {
             msg = gettext('User name \'%s\' already exists', state.username);
             setError('username', msg);
@@ -172,7 +172,7 @@ class UserManagementCollection extends BaseUISchema {
       if (obj.isNew(state) && obj.top?._sessData?.userManagement) {
         for (let i=0; i < obj.top._sessData.userManagement.length; i++) {
           if (obj.top._sessData.userManagement[i]?.id &&
-            obj.top._sessData.userManagement[i].email == state.email) {
+            obj.top._sessData.userManagement[i].email.toLowerCase() == state.email.toLowerCase()) {
             msg = gettext('Email address \'%s\' already exists', state.email);
             setError('email', msg);
             return true;