No way for a 3rd patry earphone damage the iPhone, either the 3rd party earphone works either it doesn't. iOS doesn't allow 3rd party hardware communicate with it in a way that it can mess it up. I've used 2 differents earphones and a headphone on my iDevice and without messing iOS issue. But i should say that i've experience this only with iPhone 4 and maybe earlier version of iPhone are have weak iOS.