Portrait of the Week - Sisters

I found this picture a few years ago. I'm thinking by the garments and hairstyles that it most likely dates to the late 1880's or 1890's. 
They look like sisters, probably close in age. I have been calling the one on the left Martha and the other Eunice. I feel like they were just two peas in a pod. So much so, they probably held each other's hand mirrors after the ritual of  pinning up their hair. I'm sure Martha learned the harmony to all of Eunice's piano concertos, so the piece would sound just as it was written. Eunice loved hot blueberry pie and Martha liked ham and eggs.
This picture was taken in Sandwich, Illinois.