Client entered a duplicate check, and later reversed the first check. After posting, reversed checks were printed and purged.

She also wanted to reverse the second check.
When second (duplicate) check was reversed, a data integrity error was created because the reversal was applied to the first check, not the second.

Rebuild created an entry to balance it so now the Vendor account has
MC outstanding amt = -300, original amt = -300
RC outstanding amt = 300 , original amt = 300
Data Integrity reports no errors

The Open Payables report shows the two open transactions:
MC -300 and RC 300

However the Overdue payables report shows only the RC 300.
The Vendor before this one on the report has one invoice duplicated and on the same line the -300.

The totals on the reports match, so the error is in the details and their display and not in the calculated totals.

Why did re-build create a transaction that is impossible to apply or resolve, and how do we fix this?