Hi,
If you want to refresh solman sandbox system from Production system. Then, I would suggest you to take approach of Export/Import. If you will use database restore option then you will face lot of problems to bring your As Java part up. Also, database refresh using DB specific method without As Java export of dual stack system is not recommended by SAP. Please check SAP note 795779, 529769 & 1797014.
Also, client copy in solution manager has some limitations like it cannot copy cross client data. Please refer to SAP note 1899335.
Thanks
Sunny