diff --git a/ChessCubing.App/Pages/ApplicationPage.razor b/ChessCubing.App/Pages/ApplicationPage.razor
index dc843c5..f6f877d 100644
--- a/ChessCubing.App/Pages/ApplicationPage.razor
+++ b/ChessCubing.App/Pages/ApplicationPage.razor
@@ -160,7 +160,7 @@
                             </button>
                         }
                     </div>
-                    <input @bind="Form.WhiteName" @bind:event="oninput" name="whiteName" type="text" maxlength="40" placeholder="Blanc" />
+                    <input @bind="WhitePlayerName" @bind:event="oninput" name="whiteName" type="text" maxlength="40" placeholder="Blanc" />
                 </label>
 
                 <label class="field player-name-field">
@@ -178,9 +178,14 @@
                             </button>
                         }
                     </div>
-                    <input @bind="Form.BlackName" @bind:event="oninput" name="blackName" type="text" maxlength="40" placeholder="Noir" />
+                    <input @bind="BlackPlayerName" @bind:event="oninput" name="blackName" type="text" maxlength="40" placeholder="Noir" />
                 </label>
 
+                @if (!string.IsNullOrWhiteSpace(SetupError))
+                {
+                    <p class="profile-feedback error span-2">@SetupError</p>
+                }
+
                 @if (IsAuthenticated)
                 {
                     <section class="setup-social-card span-2">
@@ -379,6 +384,7 @@
     private bool IsSocialLoading;
     private int _knownSocialVersion;
     private string? ConnectedPlayerName;
+    private string? SetupError;
     private string? SocialLoadError;
     private string? InviteActionError;
     private SocialOverviewResponse? SocialOverview;
@@ -387,6 +393,26 @@
 
     private string SetupBodyClass => UsesMoveLimit ? string.Empty : "time-setup-mode";
     private bool CanUseConnectedPlayerName => !string.IsNullOrWhiteSpace(ConnectedPlayerName);
+    private string WhitePlayerName
+    {
+        get => Form.WhiteName;
+        set
+        {
+            Form.WhiteName = value;
+            SetupError = null;
+        }
+    }
+
+    private string BlackPlayerName
+    {
+        get => Form.BlackName;
+        set
+        {
+            Form.BlackName = value;
+            SetupError = null;
+        }
+    }
+
     private SocialFriendResponse[] OnlineFriends
         => SocialOverview?.Friends
             .Where(friend => ResolveOnlineStatus(friend.Subject, friend.IsOnline))
@@ -563,6 +589,13 @@
 
     private async Task HandleSubmit()
     {
+        SetupError = ValidateDistinctPlayers();
+        if (!string.IsNullOrWhiteSpace(SetupError))
+        {
+            StateHasChanged();
+            return;
+        }
+
         await Store.EnsureLoadedAsync();
         var match = MatchEngine.CreateMatch(Form.ToMatchConfig());
         Store.SetCurrent(match);
@@ -581,7 +614,10 @@
     }
 
     private void LoadDemo()
-        => Form = SetupFormModel.CreateDemo();
+    {
+        Form = SetupFormModel.CreateDemo();
+        SetupError = null;
+    }
 
     private void FillWhiteWithConnectedPlayer()
     {
@@ -590,7 +626,7 @@
             return;
         }
 
-        Form.WhiteName = ConnectedPlayerName!;
+        AssignConnectedPlayerToWhite();
     }
 
     private void FillBlackWithConnectedPlayer()
@@ -600,7 +636,7 @@
             return;
         }
 
-        Form.BlackName = ConnectedPlayerName!;
+        AssignConnectedPlayerToBlack();
     }
 
     private async Task InviteFriendToPlayAsync(string friendSubject, string recipientColor)
@@ -699,6 +735,53 @@
 
         Form.WhiteName = session.WhiteName;
         Form.BlackName = session.BlackName;
+        SetupError = null;
+    }
+
+    private void AssignConnectedPlayerToWhite()
+    {
+        if (!CanUseConnectedPlayerName)
+        {
+            return;
+        }
+
+        var connectedName = ConnectedPlayerName!;
+        Form.WhiteName = connectedName;
+
+        if (SamePlayerName(Form.BlackName, connectedName))
+        {
+            Form.BlackName = "Noir";
+        }
+
+        SetupError = null;
+    }
+
+    private void AssignConnectedPlayerToBlack()
+    {
+        if (!CanUseConnectedPlayerName)
+        {
+            return;
+        }
+
+        var connectedName = ConnectedPlayerName!;
+        Form.BlackName = connectedName;
+
+        if (SamePlayerName(Form.WhiteName, connectedName))
+        {
+            Form.WhiteName = "Blanc";
+        }
+
+        SetupError = null;
+    }
+
+    private string? ValidateDistinctPlayers()
+    {
+        var whiteName = NormalizePlayerName(Form.WhiteName, "Blanc");
+        var blackName = NormalizePlayerName(Form.BlackName, "Noir");
+
+        return SamePlayerName(whiteName, blackName)
+            ? "Le meme joueur ne peut pas etre renseigne des deux cotes. Choisis deux noms differents pour Blanc et Noir."
+            : null;
     }
 
     private bool ResolveOnlineStatus(string subject, bool fallbackStatus)
@@ -719,6 +802,17 @@
             ? "blanc"
             : "noir";
 
+    private static string NormalizePlayerName(string? value, string fallback)
+        => MatchEngine.SanitizeText(value) is { Length: > 0 } normalized
+            ? normalized
+            : fallback;
+
+    private static bool SamePlayerName(string? left, string? right)
+        => string.Equals(
+            MatchEngine.SanitizeText(left) ?? string.Empty,
+            MatchEngine.SanitizeText(right) ?? string.Empty,
+            StringComparison.OrdinalIgnoreCase);
+
     private void ResetSocialState()
     {
         SocialOverview = null;