Yah i'd guess nin and mnk share gear.
so if you take 2 melee to a pt, it will be drg and nin, probably. Or all 3
If you're a static, or farm group, you'll just have to fight over it, you'll get your stuff eventually.
it's really not different from 2 mnks, or 2 drg, fighting over same gear.
would only be bothersome in 2nd coil, because of lock-out.