Steps to reproduce:

1. Precondition 1: The template T have hostgroup A, graph G and is linked to host H which have hostgroup B.
2. Precondition 2: User U have user type "Admin"; have read-write rights to hostgroup A; have deny rights to hostgroup B.
3. Login as user U.
4. Navigate to Configuration -> Templates and choose Graphs of template T.
5. Click on graph G to edit.
6. Change the graph name and click Update.
7. Navigate to Configuration -> Hosts and choose Graphs of host H

Result:
Besides the graph with the new name, the graph with the old name exists in the list of the graphs.
See database table "graphs": the host graphs with the old and new name, have the same value in templateid column.
Expected:
The name of existing host graph is updated, no new graph created.
The template graph can be inherited only to one graph in scope of the host.