Okay, this is just a theory, but hear me out.

In the "SONIC CD 6290 MIX" and "SONIC AFTER-6290 MIX," 6290's a number in both of the two Ogata tracks. 6290 doesn't have a reason... until you turn it into a date.

Then, you get June 2nd, 1990- which is dangerously close to when TTS 1990 started: June 7th, 1990. June 2nd might have been the date when Sonic 1's first prototype was dumped.

I have no idea if this is true, but it seems very much like it.