As I was listening to Exo-K/M's song Mama last week, I felt the chanting from the beginning was really familiar to me. Since I am a lazy fuck I didn't look for the original at first, then as I watched the MV for the first time it all came back, it was from this song from a crappy French movie !!!
And the "original" melody felt already familiar, as lydzi pointed it out here.
Copying a song that copies another song, not a problem in K-pop !
Source: My mad memory, my yt, and youtube. And if you're interested in the movie the soundtrack is in here