If it's the same driver in both cases and he was acquitted of the 1999 incident, he has no driving convictions so could fairly claim in the most recent case to have an unblemished record, not least because that's what he has.
The circumstances of the 1999 case are far from clear, it was rather early for a death by dangerous prosecution because they generally didn't get underway until a few years later.
In the other thread, the victim's girlfriend mentions an inquest, which there would have been.
I wonder if the 1999 driver was ever prosecuted - the girlfriend wouldn't be the first person to confuse an inquest court inquiry with a criminal court prosecution.
The reason death by dangerous was created was because it was felt too many fatal road accidents equated to a 'free kill' for the at fault driver.
The offence is part of the 1988 Road Traffic Act, but that doesn't help a great deal because it wasn't fully enacted until some years later.
As I said earlier, I can't recall any death by dangerous prosecutions much before the early 2000s, but I'm happy to be corrected about that.