No. It doesn't. What you are forgetting (or not realizing) is that the DFA damage reflects TWO attacks. Each attack has a chance to hit and deal half the listed damage. So, each 'hit' with a Hatchetman DFA does 55 damage to the target. The Hatchetman then also takes 55 damage to each leg (for 110 self damage).
The Vindicator (also a 45 ton mech) does 110 damage with a DFA also.