Impex Problem (merging two databases)

[Narutoboy]

I'm trying to use Impex to merge two databases into a blank forum. Every time I try and do it, though, the system will automatically merge certain accounts, while others are completely untouched and given import id tags. For instance, my user id was 4 and my account was merged with an unrelated user on board #2. His id was also 4. How do I stop this from happening?

[kpmedia]

Impex shouldn't automatically be doing this.
Re-read the Impex documentation. I know this issue is referenced, in how to address duplicate usernames.
It's been about 10 months since I last used Impex, so I can't go off memory.