what if the 3rd party battery grips came out before the canon one does?

How do they make them anyways, do they have to dissect the originals and re create them cheaper? I got a cheap one for my t2i and it works great except the battery indicator does not work, it just goes from full to dead(not a huge deal as I have a feel for when it is about to happen anyways). does this happen with other 3rd party grips as well?