I have a friend with an NTL connection. Over the past 6 months or so, some of us in his address book (not everyone though) have been receiving emails from him in multiples. Sometimes it can be 2, sometimes it can be up to 6!! Not everybody that receives multiples receives the same amount every time. e.g. If I receive 4 today, another may receive 3, etc.
In the past I have scanned his PC with the online facilities, scanned with AVG and Norton, no viruses or anything found. I have installed Spybot and removed all of the crap that he had on his drive, he also uses Zone alarm.
I am at a loss what to suggest next, apart from it maybe being NTL's servers! I received 2 messages, 3 times each last night and I have now received them both 3 times more this morning!! This itself leads me to think it is an NTL problem due to the fact his PC hasn't been switched on this morning!!