That's unfortunate.
I think you can tell if it's refurbished or not by examining the packaging. I don;t think they replace it so if it looks unopened the psu was new.
Wrt to chances of a second one dying, we don't really know the causes of the deaths. If it were regular wear for the first one and QA stupidity for the second, yes I'd estimate that you are particularly unlucky. Seasonic is supposed to be the best PSU manufacturer out there, as already noted by others