Well they can grow out in large mats, but they are fairly passive. Like xenia they are considered a pest by some just because they can grow fast and in large colonies, but xenia can grow much larger polyps and be a bit more of a nuisance.
Honestly I like the clove corals, they can be very pretty and dont harm other corals. They can however grow to a point where they can take over a small tank in a short amount of time, so really up to you whether you want them or not. I would prolly just try and contain them to one area and try and frag them off of the places that you dont want them.
Of course that it is if they are actually cloves. A pic of them would help to be sure that is actually what you have