Honestly, I know multiple people who got a drop off each boss. Even with 2 Bosses up, the group mentality still focuses on one first, and when that one died the second had been hardly touched, which is plenty of time for the top players to get onto the top of the list on that boss as well.
Getting into the top 20 is a lot easier for people who don't usually get drops than it is getting into the top 10. I haven't spoken up about this subject before, because well, I enjoy getting more than 1 drop at an event. But honestly, I hardly play anymore.
*IF* you want to spread items around to people/templates that usually dont get items, then take into account the following:
1. The TOP damager + TOP item getters are currently THROWERS/ lesser degree Archers. <- These DOMINATE events on EVERY shard.
2. The second top item getters = Spellweavers AKA Word of Death users.
3. Tamers arent much of an issue nowadays, as its really hard for a dragon to outdamage a thrower/WoDer now.
If you want some change in who gets items you can do the following:
1. Turn off WoD (Ive seen it on Event Bosses before)
2. Make the Bosses Anti Range (Like tentacles of the harrower for example). Or don't let them get AI'd.
3. Eat Pet if you really want to negate tamers (Although like I said, tamers are hardly an issue atm IMO, and this causes more grief than is needed).
Of course, I don't recommend doing stuff like this on every Boss as really, it starts becoming unfair negating a whole template/character over and over. But for when you want to switch it up for awhile, that's the best route you go.
Anyways, sorry for the mini rant. At the end of the day, not only does my guild get a good chunk of items, but so do I. And if I happen to NOT get a drop, well I just use my vast UO fortune to buy it.
(I want to mention, that I remember an event on Deceit with 4 bosses you did Bennu, I believe it was the zombie painting or some such. That actually seemed to work decently well. But again, alot of people got multiples (like myself). The important part was their spacing, as it took some time to go between bosses. If more than 1 boss are going to be used, I do reccomened there be some travel between them, and for them to be up at the same time. This will also help Lag, while making it harder for those top players to easily switch and keep damage up on both bosses.)
