Thanks both so far.
I don't have the actual pictures but have asked the person who does have them to have a look on the back.
As far as my family are concerned the uniformed chaps are the same person, Robert McGuire born 1896 in Glasgow.
I've been doing a lot of work on family tree and had already discovered that his brother, William John born 1888 Glasgow, emigrated to Canada in 1912 and signed up for Canadian Forces 1914 until discharged 1919 as a driver in 39th battery artillery.
There were no other brothers in the family and, so far, no other candidates for who could be uniformed. But, I can't find any service records for Robert. His parents are William and Mary and he was unmarried until 1921 and addresses of Roberts with records dont match so far.