The two Mona Lisa's. Both authenticated as being painted by Leonardo, notice the age difference between the two versions. It is believed that Leonardo painted her twice, ten years apart.
Haha. I think you have added yet another mystery to the oft discussed paintings.
I watched a "NOVA" program, a year or so ago, about the two paintings and the family of Mona Lisa. There are still some extant records that demonstrate that her husband was wealthy, so it can not be because she lacked funds for a large wardrobe. Curious.
Maybe the dress had some very special significance for her ? Is it possible we are looking at a wedding dress ?