Backup Plugin - Weird File Names
If you have the Exploit Scanner tool, run it on the site to see if there has been any malicious code inserted into any other the site files:
You host may have scanning tools as well. Those weird file names should not be there.
Let me know what the results are. If it turns out that the site has been hacked, here is a good resource to help:
Damon Edis - interactivetools.com
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