is the original clear coat on my 2003 corvette bumper harder than new clearcoat after repair

Clear coat is actually becomes harder as it bakes and its because of a chemical reaction that is mixed in it. The problems you have, sound to me like a lazy painter or a bad shop. When the clear coat is dull, that usually says to me that the painter mixed it wrong or had a bad gravity feed gun or siphon feed. The nicks and the chip, that could be caused by dust. When the painter is clear coating, no one is suppose to be walking in and out of the booth... main reason: dust. When you walk around in the booth it picks up dust and lays on the clear... which in return, causes nicks, fish eyes, or cause the clear to chip cause the clear couldn't adhere to the base correctly. My advice: go to another shop that has a good reputation and ask them to explain to you how they paint their vehicles. Clear coat takes 24 hours to cure, and after curing it needs to be wet sanded and buffed out.