Essor Prof
Anyway, I've checked more than 50 coins, most of them are with normal heart of with DDO, I've only found a few with hole in the heart without DDO:

So there are indeed 3 different varieties:
- Normal heart
- Hole in the heart
- Hole in the heart with double die of the heart and crown
All the coins I've found have mintmark ♥•G•J. I strongly believe the ♥•G•S mintmark in the first year line is a typo and just had to be ♥•G•J. There are no other coins in Greenland nor Denmark with that mintmark and:

It would be totally illogical to have a ♥•G•S mintmark in 1926!
I looked through multiple auction houses and Ebay pictures, and came to the same conclusion. I couldn't find a single one with ♥•G•S. Neither NGC, nor PCGS don't list that mintmark as well.
So, I guess my coin is "Hole in the heart" DDO?