I think the original doors were always the top colour. I think it would be difficult trying to separate the colours in the gel coat of a mold. If they could, matching the colour lines of door to body would be even more difficult.
I agree that on certain trailers the 2 colour door looks good. But it is a sure sign the trailr has been painted. For me, I had FG damage on the top and door but not the bottom of my boler
American. I'll be doing the Zep thing restoring the original green and painting
the top and door white. Trying to keep the "original" look.