See, the thing about the 1+1+1 is that they can't all die at ONCE. Even moving at a reasonable clip, let's say that trolley kills say, one person a second. Two people per second already die anyway, so yes, we're increasing the mortality rate, but humanity can survive that, and statistically a lot of people wouldn't end up dying by trolley. It would SUCK that there's a chance you might wind up on the trolley and dead at any time, but dying is already a natural part of life and it happens to everyone at some point anyway, so there's nothing inherently STRANGE about adding a trolley death every second.

The 100 reincarnating people will be suffering FOREVER, repeatedly, with no reprieve or redemption, and the real kicker is all the other people in the other lane are dying ANYWAY, just as people always have, so it's not like you've really SAVED them - you've just not allowed the mortality rate to increase at the cost of eternal suffering for a few people. Doesn't seem like a good trade.

It's a more interesting question if we change it slightly and all of the infinite people are Wolverine, bub.