Crash Bandicoot Purple: Ripto’s Rampage + Spyro Orange: The Cortex Conspiracy have two completely different single player games but share the same multiplayer modes. You can also trade cards between both cartridges. Just keep in mind, this isn’t like two version of Pokemon, for comparison.
There are a couple different Single-Pak multiboot modes – a Pong clone and a top-down action game. However, there are 5 variants of each, which is rather unique especially for a Single-Pak experience.
This is Single-Pak link!