No, that's not a mirror!  It's the twins, Martha and Margaret.
The Twins
Martha Isabel and Margaret Adele were the twin daughters of
Herman and Ida May Weyland.  By a stroke of good fortune, the
owner of the Ross photo studio in Tipton was a neighbor of the
Weylands and, intrigued by the unique opportunity to photograph
identical twins, Mr. Ross took a number of photographs of the
girls.  Some examples appear below and on the following pages.

With a little practice, it's actually easy to tell the twins apart.  
Margaret's face is slightly more rounded than Martha's and her
cheeks are fuller.  Martha's chin is a bit longer than her sister's.  
                           Martha and Margaret.  
The Twins as infants, with Margaret on the left.