There are oodles of Cassons, and it seemed to me when I was trying to hunt down parentage of "my" William Casson ( mine married a Mary Blenkinsop, and was a lot younger than yours, although I've had huge problems with him, over the years) - that all of them were called William.
But don't despair.
I managed to untangle quite a few away from my one by finding out the jobs they did - mine was a cabinet maker, and that sorted him out from the others who were shoemakers, weavers(!) and farm labourers. It's often a good idea to try and find out occupation, I found that in another of my Cumberland lot, generations after generations were cabinet makers, joiners or shipwrights.
Good luck with your search.
TY