Twins

No, not Tegan and Sara. Although they are twins...
Anyway, this time it's The Cribs. They're made up of a set of twins and their cousin. Anyway, their song "Martell" was in a commercial for... Telus? Anyway, after about a year of listening to it with out noticing any particular thing, I listened to it one day and realized: the second verse is sung by a different voice than the first one. I made my sister listen to is, and she didn't believe me. I made my neighbour listen to it, and she didn't believe me. I made her listen to it again, and she said, "Oka, maybe he's singing in a slightly different tone." No, Savannah. No.
Then I checked the music video and, sure enough, I was right (of course; was there ever any doubt?). The second verse is indeed sung by a different member than the first is.

Suck it!