Simple question about restoring a backup on a NAS

Hello,

We are using Acronis True Image 2013 to backup files from our 2 NAS. The files are correctly saved on a USB drive.
Yesterday, after a problem, we decided to restore a backup containing 120,000 files (so from the USB drive to one NAS). Once the restore finished, we saw that characters had been added to the file names (at the beginning or the end of the name).
We tried to restore the backup on a regular disk: no problem. No character added.

So here is our question: why characters have been added when restoring the files on the NAS?

I hope that someone will give us a solution
Sincerely