I'm doing 2 arts, one is TKD, and the other is a little mix with a little TKD in it. They aren't so similar. As a matter of fact, the other realy only has TKD kicks (in relation of the 2), and the rest is different in some ways. I say that there's enough differences to make it difficult to get confused, but similar enough to compliment each other. I've noticed my blocks, kicks, and punches have gotten a lot better as a result of taking up the other art. I love the newer one, because it has more of what I want out of MA training. I've always liked throws, and wasn't quite getting enough in my original due to no padding, etc. Also, we're doing weapons and I've had a couple of weapons (like the staff, escrima, etc.) that I've been interested in learning! I really just wanted to become a bit more well rounded, and I'll always love my original choice.