Each time when a cd/dvd is inserted or when a cd intialization function is called, some sort of checking might be performed to know whether it is an original PS1/PS2/DVDV etc etc. Now If this procedure is interpreted by some memory resident program, then that program checks the dvdv disc, validates and sends the necessary values to the calling program expecting the value to be an original or PS2-DVD .
disc is validated by the mechacon chip - psx/ps2 disks contain some data in pre-data ring on the disk, which is impossible to replicate by burning the disk, and is accessible only by ps2 drive hardware. if the disc is invalid the drive will reject the disk, at hardware level (supposedly).
also mechacon decrypts some portions of the disk, e.g. playstation2 logo that appears on disk start.