Whoa, I missed the post of the zippers until just now. From those pics it appears the zipper was added after manufacture. However, the most critical place to check for that isn't shown in any of the pics
Specifically the zipper's stitching on the left side (as you wear it) as seen from the outside of the jacket.
What you are looking for are signs that the zipper could not have been sewn "on top" or clear signs that it was patched in. Different thread type/color, stitch counts (how many stitches per inch), straightness, etc. It is also very useful to see how the zipper (or any other item for that matter) stitching is integrated into the rest of the stitching. For example, at the top of the left side where it meets the collar. Did someone pop some stitches in the original collar's stitching, insert the top of the zipper, the restitched? It's hard to tell from the picture, but if that is the case then I'd say it was put on after original manufacture.
Now, here's a twist. Sometimes the initial production is officially modified to test out a possible improvement. Therefore, it's entirely possible that the Danish MoD asked, and paid for, these zippers to be put on. If that is the case then it's an experimental item by every meaningful definition.
I have an example of an experimental item from a standard production piece. Early on (1991?) the Bundeswehr experimented with a 4 pocket version of the standard Flecktarn shirt. They produced a fair number with lower pockets assembled from the same cloth and snaps as the standard shirts. I don't know if the factory that made the shirts did the modification, just for sure the pockets were added to shirts that were unissued. I've only seen a couple and they have the same labels. They were issued to a single unit (or so I've heard) for testing.