if the tank is big enough, you'll probably be alright as long as you choose bigger plecos that can handle there own and wont get bullied out of food. just watch them
how wide is it? you can keep a whole lot of plecos together in that size tank. but i personally wouldn't have 2 2ft plecos in that size tank. but temp. definately put another few in. how big is that adonis now?
what happen after that??he goes on a rampage??? kill the rest of the plecos?at 4" you'll be able to have quite a few more plecos in that size tank for probably a good few years