Hi
After such client copies it is always better to delete the existing Sites in the transaction ( SMOEAC - Administration Console ) and recreate them with their subscriptions.
If any inconsistency is there it will be shown when you try to modify or delete the sites.
These are the 2 table which gets updated while you create New Site or modify existing ones SMOHSITEID and SMOF_ERPSH.
After the client copy these table are likely to be corrupted. Check for any inconsistency in this table.
In my case ECC quality site id (GUID) was replaced with Production Site id (GUID) In above tables after the client copy from Production to quality.
Regards,
Chella.