Copying isn't okay.
Copying is just... Sad. It really shows how much of a creative person they are.
I've never been copied, since I'm not the leader type, but it has always bothered me.
I understand inspired, but copying, no. It also bothers me when they don't admit it, but just argue that "oh i magically came up with the same ideas!" and whatnot.
Their leader should just admit and apologize, even if that will be exposed to their whole group.
I'm pretty sure you worked hard on making the ranks and system, why don't others just appreciate and respect it?