Hi Stan,
Some background: Up to now I had been using an older version of EBH and had the tendency to use it at the same time as the mailings being done - for example checking every 10 minutes to pick up the bounces on lists of about 8,000 addresses. There was never any trouble with this, the bounces added up perfectly and there didn't seem to be any interference between MBM and EBH. I have used the new version of EBH anticipating the same behavior (on my shorter list) but perhaps that triggered the error for the not summing up of the bounces. No double emails though.
The curious aspect was that I have received quite a few bounces from businesses related to the automobile industry, which have never been on my lists and on my computer in any way. I could assume that some spammer had decided to use my "from" address as their own, and perhaps they were spamming the Spanish automobile industry, with their bounces coinciding in time with my bounces - both arriving in my mailbox. But this is too coincidental because after EBH deleting the bounces from the server, I've had no more bounces. In any case I recovered last week's "real" bounces and I'll be sure not to work EBH and MBM simultaneously. As the bounces were deleted I can't see the headers to give you any details unless they are recorded in EBH somewhere I don't know. I'll let you know if the same mystery bounce addresses show up next week for the next mailing.