I only own four PSX discs. However, I went to the trouble of reading the ringcodes for all four of them.
However, I've noticed an odd trend.
Three of my four discs have the EXE date off by one day. All of them match the database.
Alundra (USA) (1.0)
The Database's EXE date is 1997-11-29. My copy has it as 1997-11-28
Tekken 3 (USA)
The Database's EXE date is 1998-03-31. My copy has it as 1998-03-30
Tiger Woods 99 PGA Tour Golf (1.1)
The Database's EXE date is 1998-10-29. My copy has it as 1998-10-28
My copy of Spyro 2 has a matching date.
Is this a time zone issue? I live in the Eastern Standard Time zone (UTC-5). I've heard that many early PSX dumpers were European. That might be the problem.