I don't see anything wrong with the ammo from the Hornady boxes. Hornady probably doesn't make their own 7.7x58 brass so different lots having different headstamps really doesn't surprise me. The boxes do, however, look pretty worn for being new off the shelf.
In any case it appears all the fire forming was done in the OP's rifle. 7.7x58 has a shorter neck than '06 but the really short necked fired case is a result of the 7.7 being fired in a .30-06 (or other) chamber. We really don't know what the OP's rifle was rechambered to, only that a .30-06 will fit....
'06 is a good bet though since it was a common conversion for a bring-back rifle with no local ammunition availablility.
The case on the left fireformed more because it was softer. The one on the right didn't fireform much at all. Or maybe the one on the left just had a better neck seal, who knows.