Thank you once again Xinia for this, being able to view the subjects side by side, does make it a whole lot easier to be able to compare the images.
These CdV's came from a distant cousin [a descendant of Joseph KENDALL] they were both labelled as John, but I did not think they were the same person. IF they were both John I would have said the clean shaven image would have been the younger man and the bearded one when he was older. As the clean shaven one was taken post 1873 [from the second premises listed] and John died in 1875 it does rule out this possibility.
Their are similarities between the known image of Tom and the London CdV are very apparent. I did know that Tom's lady love requested he shaved off his beard then she would accept his marriage proposal [Though the two did not marry an Tom was later sued for breach of promise.]
I am little uneasy as to the suggested date the photograph was taken and the London CdV is feint [seems a poorer image] so could this in fact be father and son and the London CdV a copy of an earlier image of John, perhaps as someone has suggested a memoriam.
So who could the Hull image be, if not John? This could make my 3rd option possible a photograph of brother George. I do know that the sibling Joseph was closest to was his brother George who lived in Hull in 1890. I do think both are KENDALL'S the images below are of known siblings many of whom inherited their mothers long faces and dark eyes,
The Hull CdV has slightly rounded corners where as the London CdV corners are square.