The hardware version 1.0 has been bugging me so I have been looking around at other rigol threads. It seems maybe, and I'm still not completely clear on this, but from the best I can tell, hardware ver 1.0 = non-A models, and hardware ver 2.0 = A models.
breedj, how do you know that you have an A model? Does the sticker at the top of the scope have an A at the end of the model number like in Muxr's picture above? If so does it look like the sticker has been tampered with at all? Since you purchased this scope second hand it I'm assuming you don't have a warranty for the scope so it might make sense to open it up. The hardware version should be printed on the main pcb once inside. Also you could check for the actual 50Ohm hardware, my understanding is you would see a relay & 50Ohm resistor for each channel right by where the bnc connects to the pcb. I believe on the A models you would also find an unpopulated area on the pcb for the MSO hardware. If the sticker on the top of the scope does say its an A model, it could also be possible that the person that sold you the scope, originally bought non A model, then later bought an A model and swapped the guts so he could sell the non A as an A. Of course if it doesn't bother you, or you don't want to go through all this extra trouble, 50Ohm feed thru terminators are certainly an option. I'm really just hoping that the seller didn't rip you off, hopefully you paid close to what other used DS2072's are going for and didn't pay for the "upgrades" since they are so easy to do yourself. But thats between you and the seller, ultimately if you are happy with the scope and feel like you got what you paid for, then thats all that really matters.
Edit: I'm still not very comfortable with my first statement, so please don't take it as fact. Maybe some non-A owners could chime in with their reported hardware versions?
Edit2: Also meant to include this link to the SCPI commands to turn on and off 50Ohm termination mode if you scope has the hardware.
https://www.eevblog.com/forum/testgear/rigol-ds2000-hardware-version-2-0/msg272887/#msg272887