So, you are suggesting to injur the anemone to prevent it from growing?????
If a tank isn't big enough to house an animal in its adult form, it shouldn't be in there in the first place!
I wish people wouldn't say "frag the anemone". It is wrong. You are not fragging it, you are injuring it, almost like cutting a starfish in half, so you can have two!
Anemones can have the ability to regenerate, but forcing the issue is completely irresponsible reefkeeping. Forcing the issue to prevent it from overgrowing an undersized tank is even worse.
An Anemone isn't a colonial group. It is a single animal. You wouldn't frag your dog, or a horse or a fish...why try to cut an anemone in half? To save money? To try to sell one and make money? Because it doesn't fit in an undersized tank?