Fix adding multiple interpolated expressions with the same format to admin logs

Add test case

Content.Shared/Administration/Logs/LogStringHandler.cs

@@ -40,7 +40,23 @@ public ref struct LogStringHandler
             format = argument[0] == '@' ? argument[1..] : argument;
         }
 
-        Values.Add(format, value);
+        if (!Values.TryAdd(format, value))
+        {
+            if (Values[format] == (object?) value)
+            {
+                return;
+            }
+
+            var originalFormat = format;
+            var i = 2;
+            format = $"{originalFormat}_{i}";
+
+            while (!Values.TryAdd(format, value))
+            {
+                format = $"{originalFormat}_{i}";
+                i++;
+            }
+        }
     }
 
     public void AppendLiteral(string value)