I may as well be the only active forum member with two passports on this forum.
However, it is not uncommon to have two in Argentina.
I confess I got my Argentinian passport mostly because for sentimental reasons than for the actual need to have it (in fact, I have never had the need to). I just wanted to be able to vote where I live.
Other marginal reasons were to have the same rights as my husband in case of war or divorce with kids. So far, no war, no divorce and no kids.