I don't know if this should be like this or it is a bug. In kitpvp and other's. I think it is in every gamemode that u can use /feed and /heal. When you use /feed You can't use /heal after. You gotta wait to the cooldown. Feed count as a heal? I don't know if this should be like this. ;)
It is like this in regular Prison at least, I think its meant to be that way. If you have on potions, /feed doesn't take away the potion effects like a /heal would.