They are using the latest version, and service pack, of AP.

The first reversal was done in June when they first started, on version 8.0A.
The second was done this year after the upgrade to 8.1.

The entries cannot be ignored, since the Overdue Payables report is wrong for this vendor and for one other unrelated vendor. This appears to be a problem in the program. The Vendor transactions are correct in the Vendor accounts, except that one vendor shows 2 open transactions that cannot be applied, one an MC and the other an RC. Again, this appears to be a program problem.