Only the original Dead Island will be included on the PS4 disc of next week's Definitive Edition, Deep Silver has confirmed, with Dead Island Riptide instead requiring a separate download. A code to download it will be included in the box.
The Xbox One version functions slightly differently, however, with both games included on a single disc.
"On XB1 it is on the same disc," Deep Silver said on Twitter, replying to a fan asking whether the two games would come on separate discs. "PS4 discs don't support multiple games, so there Riptide comes as a download code."
Dead Island: Definitive Edition includes remastered versions of last-gen's survival-RPGs featuring higher-quality textures, a new lighting system and a host of other graphical improvements. It also throws in new side-scrolling game Dead Island: Retro Revenge.
The collection is due to launch on both PS4 and Xbox One next Tuesday, May 31.
UPDATE: After it was highlighted that Metro: Redux, a two-game collection shipped by Deep Silver in 2014 featured both games on a single PS4 disc, the publisher has further clarified why Dead Island is split between disc and download.
"We could've worded that better," the publisher added on Twitter. "You need a separate menu, you can't just put two games on disc the same way as on XB1."