You're Crashing, But You're No Wave by Fall Out Boy
Features vocals by Butch Walker. Patrick Stump sings the verses, Walker sings the pre-choruses and choruses. And there's at least one lead line ("in the above entitled actions we find the defendant...") sung by yet a third voice. I think it's Pete Wentz, but I don't know for sure.
None of these parts overlap. Stump's part overlaps itself at least once. There's an angelic chorus on the "guilty, guilty, guilty!" line. Harmonies at least in the choruses. In short, a metric ****-ton of vocal tracks.
Solo vocals would obviously keep Stump's and Walker's together, like the other songs we have with two lead singers (Blink-182, Linkin Park, "King of Rock," "Bring Me to Life," there's probably lots more). But since we've got harmonies now, would you assign Stump's part to Harmony 1 and Walker's to Harmony 2, since they're very clearly different voices. What about Wentz' part? And all of the actual harmonies?
I think this is why I like this song so much, even though the lyrics are kinda goofy.