Everytime I listen to "I Am Just A Girl", a nice song with Agnetha on lead vocals from 1973, I always listen closely to Agnetha's nice vocals.
But if you listen closely, you hear Bjorn singing along in the background. It is really strange to hear a man saying, "I am jut a girl, not the kind of woman men would like to meet." It just doesn't make sense.
I'm guessing that Bjorn recorded himself singing so that Agnetha would be able to copy the way he was pronouncing the English words - besides, that was their first album in English. Probably Bjorn and Benny thought that no one would really listen to Bjorn singing in the background, so the just left it. :P