Ive already posted a similar topic on steam. I bought the deluxe steam version 2 pack which came with 2 D:OS games and two copies of each previous divinity game. Now i wanted to buy the source hunter dlc but steam is telling me that I already have it, which I dont. I ended up trying to buy the dlc as a gift in order to gift it to myself but it is still saying that I already own the dlc. Im pretty sure the deluxe edition i bought earlier did not come with the dlc and I cannot see the items in game anyways. Please fix this ASAP so I can use the DLC i bought.
Apparently other people that have bought the same deluxe edition on steam that I had are also having the same problem. They posted it on these forums as well as Steam's but there has been no fix or official reply.
Despite it not being listed as containing the DLC back when the Deluxe 2-pack was available (probably because the DLC, or even the idea of it, didn't exist back then), it does grant the owner the Source Hunter DLC. That's why Steam isn't allowing you to purchase the DLC (again) separately.
Now, there is an important caveat here. While it is a "2 pack", only one copy can be linked to the DLC. This same restriction is also on the newer Collector's Editions (both physical and digital) which come with two copies of D:OS. That means if you shared the 2-pack with a friend, one of you will have the DLC and the other will not. And in order for you to have the trunks and chalice show up in your game, the player who owns the DLC needs to be the host of your co-op session.