Joining 3 files problem

When I join three files with VirtualDubMod I end up with a larger file than I should have. VDM adds the second avi to the end of the joined movie. I can easily fix this by editing the last chunk out but was wondering am I doing anything wrong, can I change settings so this dosent happen?

Do you have the video set to 'Direct Stream Copy'? Check whatever you are doing against the to see if you are doing it right.

uncheck "automatically append segments" in the append and file open dialog boxes

Is that the auto-detect additional segments by filename box?? I dont need to use this feature that often but I think that's what you are referring to, will try it next time thanks for the help guys