Member numbering after import
 

I just finished an import from UBB.Threads. It all seems to work ok, but I noticed my user IDs were re-numebred starting at something like 13867 (In other words my oldest member now has a very large member number. AS if it renumbered my members starting with the next number based on the number of members I had. So if I had 13866 members, it renumbered then from 13867 and up.

What might have cause this and is there any way to fix it?