Need help in identifying painting

I know this is a long shot, but I thought I'd try. I know absolutely nothing about art, but I have a painting that's been in the family for a long time and I would like to learn about it. It is a round painting of 2 young ladies (late teens, early 20s). From what I have gathered it is Victorian. On the painting there is writing, but I can't make it out. It is dated 1839. The writing I have made out says "Marg" (possibly Margaret or Marg with...). There also appears to be "NY". On the back in pencil is written 6610/1. If anyone has any info on round paintings from the 1830s that would be much appreciated.