Buying Skyrim Legendary Edition while already having Skyrim

Steam considers Skyrim and Skyrim: Legendary Edition to be separate games. You won't be able to gift or trade the Skyrim base game, but you can purchase it and you'll have two Skyrim games in your Steam Library. I've done this several times for Deluxe/GOTY editions as well.

Edit: You can tell steam considers them to be separate games because they exist separately in the store. (Search for Skyrim and you'll see what I mean.)