One registration, two databases..
 

I know this has been asked before, but I couldn't find any recent discussions on the topic. What I want is rather simple--but I'd rather see if anyone has done something similar before I try to hack up something myself.

I am thinking about starting a new forum in addition to my current forum. These will be two separate instances of vbulletin and two separate databases. I'd like a user to only have to register at one page and it will insert their information into both databases. No other cross-integration between the sites. I'd imagine it's just a matter of switching the databases in register.php (or more specifically calling the function twice with different dbs). Has anyone done something similar? Thanks.