Steps to reproduce:
1. Create host A
2. create item A on host A;
3. Create host B;
4. create item B on host B;
5. Go to host A and create a graph X using the item A from host A;
6. Without navigating to another host, press "Create graph" again, but this time choose item B from host B and for graph name use same name X;

Result: inline validation error "This object already exists."
Expected: no error and graph X is created on host B with item B.

Caused by: ZBXNEXT-9736