As someone who has done plenty of indie game development, I understand their gripes, but also I know this is the "Game" we're playing here — anyone who makes any form of success should expect to be cloned. Period. So think about that from the get-go and come to peace with it in your strategy/set expectations accordingly. The second I put any app out there I assume it's out in the general "mindspace" and will probably manifest somewhere in another form at some point or another. The speed at which it manifests usually correlates to the popularity of the idea.