Must Be Love - ????

Guys I know I'm probably late or whatever but I'm baffled... I'm not a Cassie fan so I hadn't really bothered to listen to her track "Must Be Love".. But today I thought give it a try you may like it... so I press play...
Confusion hit... This is the song I use as my alarm... the instrumental and the lyrics sound the same but Cassie's singing it =|
I thought this was a Day 26 song =|...
Does someone want to let me know who sang it first? ...
I hope Cassie did it first cause Day 26's vocals on it sound like beauty... and hers just sound mediocre to me...
I'm sure I'd like her one if I heard it first though...