Although probably not unique this double sided Cabinet Photograph in the only such example that I have come
across. The front image picture above shows a British soldier wearing athletic garb typical of the late 19th Century.
Most regiments had established physical fitness programs established for members of the ranks and
inter-regimental competitions and exhibition were quite popular. Note the two dumb bells at his feet.

The image on the reverse of the card shows an unidentified artilleryman. I am unsure if the two images are of the
same man or not.

Cabinet Photograph
Unknown Photographer
Unknown Location
c. 1900