My sisters - identical twins - sing this sll the time. I think they mean it as an affirmation of love, loyalty and the special bond between twins.
But the twins in "Sideshow" were cojoined. They didn't have a choice, they had to spend all their lives together. They had to come to terms with it.
Sadly, my sisters have chosen to act as if cojoined, one though they're two. The irony of the song . . .