Just a guess but do they have 2 devices scanning to the same location? If so, change the name of the scan doc default on one of them.
Xerox checks the folder for the file name and if it sees the last one is DOC045.pdf the one it is about to do will be DOC046.pdf
But if 2 machines do so in a similar time frame they will both try and put their file there with the same name.
So if one is to use DOC, try the other one with D0C and see if it resolves the issue.
Failing that load the latest firmware here.
Take note I used your firmware listed as 072.010 to infer you are dealing with a 7830/7835 and not a 7845/7855 that would begin 072.040