I think both are great, and are similar, but there are also differences. Lolita is sweeter, with a much stronger anise note than Arpege PH. Arpege is much more versatile, masculine smelling and mainstream of a fragrance, but it has better longevity. I don't think they're redundant. I own both, and wear both of them (though I wear Lolita more often).
As for me personally, if I had to choose only one of them, I'd pick Lolita Lempicka Au Masculin. I wear it a lot.