A collision occurs when multiple games from the same series or multiple editions of the same game are submitted. Since you're not allowed to play the same piano twice, it must be guaranteed that the pianos are 2 different pianos, and not the same piano in both games.

The Myst series:

There are give or take 6 editions of the origial Myst game. Each of them includes 2 pianos: one on the main Island, one in the Selenitic age. In the edition "Myst ME" the piano in Selenitic cannot be played, but in the edition "Myst 2020" it can. Therefore a resolution is to have 2 submissions: one playing "Myst 2020" with the Selenitic Piano and one playing "Myst ME" with the piano on Myst island.

The Trilobyte series:

The Stauf mansion has 3 Piano-Like instruments: The Harpsicord, the Chapel organ and the grand piano. In "The 7th Guest" you can play the piano and the organ, in "The 11th Hour" you can only play the organ, and in "The 13th Doll" you can play the Piano and the Harpsichord. A resolution is hence to play the Haprsichord in "The 13th Doll", the organ in "The 11th Hour" and the piano in "The 7th Guest".