From the DMS website:
DMS3 Software v1.3 is now available for download. The only difference between 1.2 and 1.3 is improved disc validation emulation to help hide the chip whilst running the PS2 in PS2 Mode. All DMS3v2.0 chips already run with software v1.3. You don't have to upgrade a DMS3v2.0 with this file.