I feel bad for some people who didnt know any better when they started learning how to fly but failed checkrides do raise a pretty large flag. Sure you might have gone to fly freight or instructed for a few thousand hours but more then one failure is a pretty big black eye on your record that wont be overlooked. Once you get through a 121 training program unscathed you will be back on par. You need to prove that you are trainable and know how to study.

The whole reason that it is a big deal is: If you fail a checkride dont you think you would over prepare for every checkride after that?

One is ok but two is either exceptionally bad luck or you just werent giving it 100%.