diff --git a/src/ui/dtl/utils.py b/src/ui/dtl/utils.py
index ea616975..5ccc6de1 100644
--- a/src/ui/dtl/utils.py
+++ b/src/ui/dtl/utils.py
@@ -125,6 +125,10 @@ def get_classes_mapping_value(
     default_allowed: bool = False,
 ):
     mapping = classes_mapping_widget.get_mapping()
+    existing_classes = classes_mapping_widget.get_classes()
+    if hasattr(existing_classes, "keys"):
+        existing_classes = existing_classes.keys()
+
     if default_allowed:
         default = [cls_name for cls_name, cls_values in mapping.items() if cls_values["default"]]
         classes = classes_mapping_widget.get_classes()
@@ -138,6 +142,11 @@ def get_classes_mapping_value(
         other_allowed=other_allowed,
     )
 
+    if any([object_class in existing_classes for object_class in result_mapping.values()]):
+        classes_mapping_widget.conflict_notification.show()
+    else:
+        classes_mapping_widget.conflict_notification.hide()
+
     return result_mapping
 
 
diff --git a/src/ui/widgets/classes_mapping/classes_mapping.py b/src/ui/widgets/classes_mapping/classes_mapping.py
index 0877b0c5..652da78c 100644
--- a/src/ui/widgets/classes_mapping/classes_mapping.py
+++ b/src/ui/widgets/classes_mapping/classes_mapping.py
@@ -47,7 +47,14 @@ def __init__(
                 title="No classes",
                 description="Connect node and ensure that source node produces classes of type needed for this node.",
             )
+        self.conflict_notification = NotificationBox(
+            title="Conflicting names",
+            description="Some class names are conflicting. Please, resolve the conflicts before saving.",
+            box_type="warning",
+        )
+        self.conflict_notification.hide()
         self.empty_notification = empty_notification
+
         self._classes = classes
 
         self._select_all_btn = Button()
diff --git a/src/ui/widgets/classes_mapping/template.html b/src/ui/widgets/classes_mapping/template.html
index 457535d5..b079b499 100644
--- a/src/ui/widgets/classes_mapping/template.html
+++ b/src/ui/widgets/classes_mapping/template.html
@@ -1,6 +1,9 @@
 <div v-show="data.{{{widget.widget_id}}}.classes.length == 0">
 	{{{widget.empty_notification}}}
 </div>
+<div>
+	{{{widget.conflict_notification}}}
+</div>
 <div v-show="data.{{{widget.widget_id}}}.classes.length != 0">
 	<link
 		rel="stylesheet"