To my understanding, running it twice is used predominantly in High Stakes Cash games to reduce variance. Lets be honest if we get it in as an 80% favourite and lose 200K, its gonna sting... run it twice and we get sucked out on once, we break even. Yes it means we are going to only win 60% of the time and like 30% of the time we chop, but we only lose <10%.. (sure someone can work the odds
out better than me at this time, been a long day) dramatically reducing variance and allowing the player/game to continue longer.
The play is still +EV, although long term lower +EV, in that one instance we give ourselves a much lower chance of going broke. This would be particularly useful both when playing recreationally (as a pro or not) and when taking shots above our usual limit. Expected Value
is a long term concept over 10's of 1000's of hands, in reality very few people are going to play that many hands at high stakes therefore sacrificing some EV for a chop is worthwhile.