Check if sender is equal to the argument. Cancel if it doesn't match.

src/Avalonia.Animation/Animation.cs

@@ -167,12 +167,18 @@ namespace Avalonia.Animation
             var tcs = new TaskCompletionSource<object>();
 
             if (this.RepeatCount == RepeatCount.Loop)
+            {
                 tcs.SetException(new InvalidOperationException("Looping animations must not use the Run method."));
+                return tcs.Task;
+            }
 
-            this.Done += delegate
+            this.Done += (sender, args) =>
             {
-                tcs.SetResult(null);
-            }
+                if (sender == control)
+                    tcs.SetResult(null);
+                else
+                    tcs.SetCanceled();
+            };
 
             this.Apply(control, Observable.Return(true));