Security precautions before Restoring an account

You referring to a backup that was created on a different cPanel server to your own servers I presume. We have never been asked by on of our resellers to do that, but I must say, I would be cautious. What I would probably do is to google the domain(s) in the archive to see if there are any reports of malware, viruses etc being reported in the last few months and also the basics like who owns the domain, when it was registered, what kind of site it is, check cached pages etc.

For example if the domain being restored is hackersRus.TLD I wouldn't touch it. (Wouldn't host it either).

(I would also want to know who the previous host was and what version of cPanel they were running)