diff --git a/rsconcept/backend/apps/oss/serializers/data_access.py b/rsconcept/backend/apps/oss/serializers/data_access.py
index 9c3a266a..97b431f6 100644
--- a/rsconcept/backend/apps/oss/serializers/data_access.py
+++ b/rsconcept/backend/apps/oss/serializers/data_access.py
@@ -328,6 +328,10 @@ class CreateSynthesisSerializer(StrictSerializer):
                 })
 
         schemas = [arg.result_id for arg in attrs['arguments'] if arg.result is not None]
+        if len(schemas) != len(set(schemas)):
+            raise serializers.ValidationError({
+                'arguments': msg.duplicateSchemasInArguments()
+            })
         substitutions = attrs['substitutions']
         to_delete = {x['original'].pk for x in substitutions}
         deleted = set()
@@ -375,6 +379,7 @@ class UpdateOperationSerializer(StrictSerializer):
         required=False
     )
 
+    # pylint: disable=too-many-branches
     def validate(self, attrs):
         oss = cast(LibraryItem, self.context['oss'])
         parent = attrs['item_data'].get('parent')
@@ -405,6 +410,10 @@ class UpdateOperationSerializer(StrictSerializer):
         if 'substitutions' not in attrs:
             return attrs
         schemas = [arg.result_id for arg in attrs['arguments'] if arg.result is not None]
+        if len(schemas) != len(set(schemas)):
+            raise serializers.ValidationError({
+                'arguments': msg.duplicateSchemasInArguments()
+            })
         substitutions = attrs['substitutions']
         to_delete = {x['original'].pk for x in substitutions}
         deleted = set()
diff --git a/rsconcept/backend/apps/oss/tests/s_views/t_operations.py b/rsconcept/backend/apps/oss/tests/s_views/t_operations.py
index 1f9406d1..b146f209 100644
--- a/rsconcept/backend/apps/oss/tests/s_views/t_operations.py
+++ b/rsconcept/backend/apps/oss/tests/s_views/t_operations.py
@@ -270,6 +270,37 @@ class TestOssOperations(EndpointTester):
         self.assertNotEqual(new_operation['result'], None)
 
 
+    @decl_endpoint('/api/oss/{item}/create-synthesis', method='post')
+    def test_create_synthesis_replicas(self):
+        self.populateData()
+        operation4 = self.owned.create_replica(self.operation1)
+        operation5 = self.owned.create_replica(self.operation1)
+        data = {
+            'item_data': {
+                'alias': 'Test5',
+                'title': 'Test title',
+                'description': '',
+                'parent': None
+            },
+            'layout': self.layout_data,
+            'position': {
+                'x': 1,
+                'y': 1,
+                'width': 500,
+                'height': 50
+            },
+            'arguments': [self.operation1.pk, operation4.pk],
+            'substitutions': []
+        }
+        self.executeBadData(data=data, item=self.owned_id)
+
+        data['arguments'] = [operation4.pk, operation5.pk]
+        self.executeBadData(data=data, item=self.owned_id)
+
+        data['arguments'] = [operation4.pk, self.operation3.pk]
+        self.executeCreated(data=data, item=self.owned_id)
+
+
     @decl_endpoint('/api/oss/{item}/delete-operation', method='patch')
     def test_delete_operation(self):
         self.populateData()
diff --git a/rsconcept/backend/shared/messages.py b/rsconcept/backend/shared/messages.py
index d8e66b95..c8cd72a9 100644
--- a/rsconcept/backend/shared/messages.py
+++ b/rsconcept/backend/shared/messages.py
@@ -22,6 +22,10 @@ def operationNotInOSS():
     return 'Операция не принадлежит ОСС'
 
 
+def duplicateSchemasInArguments():
+    return 'Аргументы не должны содержать повторяющиеся КС'
+
+
 def blockNotInOSS():
     return 'Блок не принадлежит ОСС'
 
diff --git a/rsconcept/frontend/src/features/oss/dialogs/dlg-create-synthesis/tab-arguments.tsx b/rsconcept/frontend/src/features/oss/dialogs/dlg-create-synthesis/tab-arguments.tsx
index 228247d2..7ebe544c 100644
--- a/rsconcept/frontend/src/features/oss/dialogs/dlg-create-synthesis/tab-arguments.tsx
+++ b/rsconcept/frontend/src/features/oss/dialogs/dlg-create-synthesis/tab-arguments.tsx
@@ -20,8 +20,11 @@ export function TabArguments() {
   } = useFormContext<ICreateSynthesisDTO>();
   const inputs = useWatch({ control, name: 'arguments' });
 
-  const references = manager.oss.replicas.filter(item => inputs.includes(item.original)).map(item => item.replica);
-  const filtered = manager.oss.operations.filter(item => !references.includes(item.id));
+  const replicas = manager.oss.replicas
+    .filter(item => inputs.includes(item.original))
+    .map(item => item.replica)
+    .concat(manager.oss.replicas.filter(item => inputs.includes(item.replica)).map(item => item.original));
+  const filtered = manager.oss.operations.filter(item => !replicas.includes(item.id));
 
   return (
     <div className='cc-fade-in cc-column'>
diff --git a/rsconcept/frontend/src/features/oss/dialogs/dlg-edit-operation/tab-arguments.tsx b/rsconcept/frontend/src/features/oss/dialogs/dlg-edit-operation/tab-arguments.tsx
index 7936df75..3155c02a 100644
--- a/rsconcept/frontend/src/features/oss/dialogs/dlg-edit-operation/tab-arguments.tsx
+++ b/rsconcept/frontend/src/features/oss/dialogs/dlg-edit-operation/tab-arguments.tsx
@@ -15,10 +15,11 @@ export function TabArguments() {
   const { manager, target } = useDialogsStore(state => state.props as DlgEditOperationProps);
   const args = useWatch({ control, name: 'arguments' });
 
-  const references = manager.oss.replicas
+  const replicas = manager.oss.replicas
     .filter(item => args.includes(item.original) || item.original === target.id)
-    .map(item => item.replica);
-  const potentialCycle = [target.id, ...references, ...manager.oss.graph.expandAllOutputs([target.id])];
+    .map(item => item.replica)
+    .concat(manager.oss.replicas.filter(item => args.includes(item.replica)).map(item => item.original));
+  const potentialCycle = [target.id, ...replicas, ...manager.oss.graph.expandAllOutputs([target.id])];
   const filtered = manager.oss.operations.filter(item => !potentialCycle.includes(item.id));
 
   function handleChangeArguments(prev: number[], newValue: number[]) {