It's not really surprising. PG has said many times that they invest in people not ideas. I gather they also discuss ideas with founders and try and put them onto something other than what they applied with if it sucked.
From YC's perspective investing in several startups doing the same (or very similar) things increases the chance that at least one of them might get somewhere with it.
From YC's perspective investing in several startups doing the same (or very similar) things increases the chance that at least one of them might get somewhere with it.