A tale of two Sallys

The story starts with two apparently identical Sallys in the living room. Naked, that is.

"Damn Sally, this idea was complete BS! I mean, we are posing naked, in broad daylight..." the left Sally said in a sweet alto voice.

"Dad, just relax! It is hard to glance into the living room, and I doubt this will have any unintended side effects at all!" the other one said to reassure her clone.