Why is it that shirts are sometimes reprinted on a different color than the original version?

If people ask for a shirt to be reprinted, it's because they like the original.

I'm excited that this shirt was reprinted, but then I realized that it was on a pink shirt instead of blue. As much as I love this shirt, I don't want to be walking around looking like a giant bottle of Pepto Bismol, thanks.

I'll definitely order the shirt, but only if it's reprinted on the blue shirt it was originally on.