That is actually a brilliant question that I hadn't really thought of yet! I suppose I'll merge him into Watson since that is the name he was born with - and died with. I created his profile when I first found his son's (Ernest Clarence Ward-Watson _D: Zimbabwe/Rhodesia 1975, Known as Clary/Clarence by the family) death notice which also stated Ward-Watson, but in Willis's death notice Willis is recorded as Watson (D: 1922 Rhodesia). Both men died of carcinoma.
I'm not sure how the name got double barreled but I think that Willis's Death Notice holds a vital clue. Willis has two children named in the record, a son Clarence Ward, and a daughter Alma Watson. The two children have different mothers and I have never found the name of Clarence's mother. Alma's mother is also unknown as she signs the record as Mrs Watson.
The reason why I could never let go of the other Willis as a possible duplicate was that his mother's name was Claria (and also that I could never find what happened to the second Willis after the 1900 census ~ just in time to produce Clarence in 1903 in South Africa). It all just seems to fit so well. Shame I feel bad that he left a wife and another daughter in the States..now I have to find out what became of them. Then Clarence had a daughter named Clarice.
My guess on the Ward - Clarence's mother was probably a Ward.