As a result, you may have cars floating around with mismatched doors, some grey primer only, and some that are completely the wrong color.
Looks like Conrail needed a door, and only had and old one leftover in Penn Central Jade Green.
A prototype mismatch, photo by Ron Hawkins, as posted on RailPhotos.com
Not all mismatches are from damage. Some roads paint doors a different color for a reason - Conrail has used yellow doors to indicate clean lading only.