Marshallmel is selling a V1. The V2/2A's have been out probably 3-5 years, if I'm not mistaken. Maybe even longer.
The V2 prior to 2A was an added switch on the front to help with the volume taper/input level. Those are still on the 2A, and as mentioned, a line level was added on the back on 2A. The older V1 was still kinda loud at lower volumes. That added switch kinda switches from V1 to V2, if that makes sense. Its an input level sensitivity switch to help better control louder, more obnoxious NMV amps get to mouse fart levels. I've had them all.