I have a few years of experience with Russian tortoises, so I'll talk about their social needs and assume it has some application to the needs of the not too distantly related Hermann's.
Males can be persistent and aggressive about mating. Biting and ramming the females to get them to submit, and attacking other males, sometimes to the point of injury.
Females are generally OK with each other, but they can act territorial when it's time to lay eggs.
It appears to me that these tortoises can do quite well going solo. There seems to be no social need, aside from mating, and the presence of other torts seems stressful and can lead to confrontation.
If you get two, I'd suggest you get two females. If you want a breeding pair, then give them the largest pen possible with plenty of places for the female to get away from the male, or have a separate pen so the female can get a break. I use a separate pen to house my male when the females look stressed out.