I've been able to place more than one npc to a grid without a problem. I found my problem was working with imported spawn2 and npc tables. Your problem may simply be trash in the database. I noticed when I imported some of the move files offered in the forum using mysql, that the information imported in the gassign row of the spawn2 was trash. Looking through the code, I didn't notice anything in the mob.ccp to compensate for such an event.

Don't get me wrong, it's nice to see Sony's version of everquest available to EQEMU. But I'm not so certain that all this trouble is worth it. I'd rather see more servers like Winter's Roar who create custom databases based on their unique story line rather than rely on the availability of prespun databases. Everything is at your disposal to make your server a unique experience.