Sonic Spinball are gifts which keep on giving. Was just gonna say the Sega Master System version, but Game Gear version too.

SMS versions have some source code and source ROM data, most match, but two chunks don't. Don't want to rush to unknown prototype version, but...

As for the data, a sample.

:10350000880410018801100188011001880110024F

:10350000: Not the rom address, which is 0xf500. Maybe line number.

88041001880110018801100188011002: 16 bytes of rom code/data.

4F: Checksum most likely.

For Game Gear versions, several Genesis/Mega Drive pallets found which are not for Sonic Spinball, but something else.