That would be John Joseph Clarke on the left, or so lore has it here at Library Towers.
We've seen a few of the photographs
taken by this medical student before. Any way of establishing once and for all if this is he? Unfortunately, I think identifying the jaunty chap(?) on the right is beyond even all of your advanced Flickroonie abilities!
Photographer: J.J. Clarke
Date: Circa 1897-1904
NLI Ref.: CLAR43
Owner: National Library of Ireland on The Commons
Source: Flickr Commons