Ohhhh really? Well if people start using the threads that should put itself right. It's the migration from old site, its a nightmare because the user_id is different between the two sites!
Some# DBs have a setting that allows you to overrule/suspend the PK check for inserting data with index values you want to keep.
#well ok: Oracle does, but I can't remember what it's called offhand. Still, half the battle with these features is simply knowing they exist.