Minecraft Server -- running two servers on dedicated server

Some technical questions here.

I'm running Debain Lenny and hosting a dedicated server. My dedi has three cores so naturally the server runs on the one core. So I had the idea to run a secondary server as it'd still leave one core open for webserving. However Java will start the secondary server on the same core.

I have tried to use Taskset in order to set the affinity but it doesn't seem to matter. I've also tried running it as a different user as well as running it on a separate version of java and it still bunches them on the same core.

Anyone had any luck running two servers on separate cores?