I totally agree here, buy a completely new, matched set of cases and have them re-trenched/bored/port-matched. If that crank with those welds really did come from vitos I am very sorry to see what they are supplying. But seeing as daj has had multiple cranks come from them that didn't look like yours, I'd wager a guess your guy got the crank used from someone else, or tried to weld it up himself and just told you it was a vitos supplied crank. TDR cranks are made by crankworks if I remember correctly.
At least if the TDR crank fails in new cases we will know its something else that's screwed up!
If you're doing the assembly its your responsibility to check over everything else in the engine and make sure it isn't something else causing the problem. Something else out of balance somewhere, both cylinders firing correctly and jetted correctly, transmission bearings, clutch basket bushings, etc etc. At 9-10k rpm it doesn't take much for a few thousands of clearance to become a massive wobble and grenade parts.