This is what I bet happened. From Sage What's New 4.40 document -
The 4.40 architecture creates a relationship between the Item Transaction History table and the period posting and summary history tables. All period posting and summary history tables will now have corresponding detail transaction records. The benefit of the new architecture is that the period posting tables, summary history tables, and detail transactions tables will always be synchronized and if the period end dates are changed, the tables can be recalculated to synchronize the data.
During conversion, transaction records are reconciled with period posting and summary history tables. If the detail records do not match the summary history or period posting tables, the conversion process will now create missing detail records to force the synchronization.
So if they have imported into the period or summary history files for reporting purposes this is the mess we are going to get .... based on what this doc says...