I typically draft 2 closers as well, occasionally will draft a very low end 3rd if I'm "forced" to with no other hitters I want left on the board. I finish in the top 3 of my 12 teams leagues every year. As the season goes, if I have the opportunity to grab a guy who's next in line when the official closer goes down, I will do that if I'm not giving up anyone who's performing well. But, at draft time I typically do 2. I cannot imagine allocating 6 roster spots to RP's.
You don't tie up 6 roster spots the whole year or even after the first 2 weeks of the season. You do it so that you have Lindstrom before everyone else does (between 1:05 and 1:25, yesterday, he was gone in 8 leagues...good luck if you have meetings mid-day)