Photographer's self portrait

Wonderful cabinet card of what appears to be the photographers’ self-portrait as a gift to a friend or colleague.  It would appear to show the Mulligan Brothers shaking hands.  On the back in period pen script it reads “Columbus, Ohio, Compliments of 2 brothers to W.S. Ballor, No 28 W. Maple St.”  There is also an abbreviated city or state which we can’t decipher.   The image is in excellent condition with nice tones and contrast.  The Mulligan brothers obviously were successful as they advertise three addresses on the same block.