The "13.1" designation is an important specific update (often delivered via Adobe Application Manager in official versions) that added features not present in the launch version of CS6 (13.0):
If you own a CS6 license or are using it for non-commercial recovery of old PSD files, remains one of the most versatile, lightweight, and powerful tools in any digital creator’s emergency toolkit. Adobe Photoshop Portable CS6 13.1 -x32 X64- Multi 64 Bit
The "13.1" designation is an important specific update (often delivered via Adobe Application Manager in official versions) that added features not present in the launch version of CS6 (13.0):
If you own a CS6 license or are using it for non-commercial recovery of old PSD files, remains one of the most versatile, lightweight, and powerful tools in any digital creator’s emergency toolkit.