http://vgcollect.com/item/44397
Donkey Kong Country Returns 3D has a Dutch cover, and the cover has a watermark, which i can fix. But it also has the wrong barcode for that box. So what are we gonna do? I can make a new item for the Dutch version, or change this item to complete Dutch and make another entry.
I would not make it into the Dutch release just because there are 40 in collection. When it comes to items where this happens, I expect that 99% of the people who added it have the release as in the title. Another thing to consider is that many people may have added it to collection when there was no picture and that many people may not scrutinize things like the barcode or item number.
You should change the box art to match regular EU release (or the cart or whatever) and then make a new item for the Dutch version.
Or, that is what I would do.