Overview
When you "lock" these games together, the code reveals things you can't find in the standalone games: sonicknuckleswsonic3bin game file
Based on the filename you provided, sonicknuckleswsonic3.bin appears to be a ROM file for the Sega Genesis / Mega Drive. Specifically, it is the game Sonic & Knuckles locked-on with Sonic the Hedgehog 3 (often referred to as "Sonic 3 & Knuckles"). I suggest Sonic 3 & Knuckles (Merged) [Lock-On Simulation]
For the preservationist (RetroArch / EverDrive user): Keep it, but rename it. I suggest Sonic 3 & Knuckles (Merged) [Lock-On Simulation].bin. It is a historical artifact of how we had to play this game for nearly a decade. It’s a clever hack that solved a hardware limitation with brute force. but rename it.
Early examples of physical expansion packs and hardware-level content merging. Level Design & Persistence: