I've passed this on to John, but it doesn't hurt to put a line under the conversation here...

It looks like something bad happened during a previous period end, I'm guessing old details showed up because their 'matched' entries had gone to history and they hadn't.

I was able to correct things by:
1. Running a period end. This brought up a number of error messages stating that the record already exists in history..."ok" through them.
2. Run the integrity check. There were errors regarding transaction counts.
3. Rebuild to correct the transaction counts.