I am experiencing the same problem, at two different client sites. The tape drive was just replaced by HP at one of the sites, even though it was not failing the HP LT&T test suite. Since then, we have tried updating to the latest BE 10, with no change. The thread on this can be followed in the 9.x forum at:
http://forums.veritas.com/discussions/thread.jspa?forumID=101&threadID=50023
A Google search on this term "difference encountered in file data" brings up the interesting point that this error was produced by a bug that was fixed in one of the 9.0 updates. A possible regression or a new way to trigger the same bug?
The answers we are getting from Veritas have yet to fix the problem, and seem to change depending upon who we talk to.
-B