The main problem is that you are not matching the OEM clear coat coefficient of reflection. It was above Dupli-color's Protective Clear Coat Finish. You need to use Spray Max semi-gloss for clear coats.
Color matching technology is well established. There, you can use junky 1k (that is, slow drying) Duplicolor or whatever for the base coat. (If you enjoy waiting around.) But, for the clear coat, you need to be using a high tech product. The chemistry is very complex. My guess it that Spray Max has the patents, so they have the market's best products, but it does not really matter why. Using their 2k products will allow you to match the reflection coefficient, which is what you need to do.
If you want, you can download https://www.spraymax.com/fileadmin/user_upload/Downloads/Produkte/Prospekte/992466-SprayMax-Produktfolder_USA.pdf and go to the clear coat section. It will say you have two options, matte and gloss, but you actually have more. There are probably high gloss, gloss, semi-gloss, semi-matte, and matte clearcoats by Spray Max out there. As I said, the one I think you want is semi-gloss. (Gloss will probably be too reflective.) More specifically, I think you want 680067 semi gloss clear-coat/ (400 ml) 36+/-2 gloss units at 60° measuring angle. You don't need to sand or have multiple layers.
Different waxes will help you vary the reflection coefficient for perfect matching between these 3-5 levels, but it is better to match the clear coat coefficient of reflection so you don't need to use different waxes for each body part.
Having given what I think is the best answer, I'll now turn to what's wrong with the other 10 answers set out before me. After all, it is pretty dumb to be answering a question that was already correctly answered!
Most other answers complain about sanding. As I explain, it will have zero effect if you use enough paint on the last layer. Lack of sanding could make clear coat peel, but that's not your problem.
Incidentally, this is not popular advice, but I don't think you actually need more than a single layer with Sprax Max 2k. It will probably adhere well enough to have a single layer. It is that good of a product. You don't even need to sand off the Dupli-junk clear coat.
Before now, user35183 and SteveRacer had the best answer, saying that Dupli-color is junk. But, neither gave you a specific alternative you can use.
Several answers complain about thickness (number of coats). No, that's not your problem either. It may be good advice for painting, but it will not help you. You just need to make sure that the last layer is thick enough that the droplets combine on the surface.
Bad final top of top coat layer which will result in orange peel you'll need to sand:
Good final top of top coat layer which you won't need to sand and is best:
(The density of paint droplets needs to be enough that they combine.)
If you agree this is the best answer, upvote it. If you don't, please comment and set me strait.