no, it's not standard practice. i finished literally 3 seconds behind the winner and i was also listed as a DNF. it's just laziness on their part, and when you apply for an upgrade you should just point out and question why 3/4 of the field was listed as the same. to my knowledge, there were no official DNF's in the 4's race.
the problem with protesting the results when they are posted is that no one knows that whoever doesn't happen to appear on the unofficial results list is going to go down as a DNF. the results of this race were meaningless to me, but regardless, it's just a totally irresponsible move on their part.
although i had basically given up to avoid being taken out at 40mph, i still finished in the pack. so seeing that just added insult to injury.
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"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return." - Leonardo daVinci