Garfield: The Lost Levels

Garfield: Caught in the Act – The Lost Levels is a game that was exclusive to SEGA's paid “SEGA Channel” service. The game contains three levels cut from the SEGA Genesis/Mega Drive version of Garfield: Caught in the Act.

The reason the SEGA Genesis version of Garfield: Caught in the Act was split into two (The Lost Levels) could be due to Caught in the Act being one of SEGA of America's biggest projects. Caught in the Act was not the only game to see this kind of treatment; Sonic the Hedgehog 3 had to be split across two cartridges (the other cart went under the title Sonic & Knuckles; the Sonic 3 cart could be attached to it to play both ROMs as a single game), and the SEGA Saturn game Clockwork Knight was also split in half.

Source: TheGamesDB