That is why I am asking if dates and ages being off is normal, because I know his middle name starts with a C and he was a plumber so it's pretty easy to identify him but even in the later census his age changes +-10 years and the year he immigrated changed.
I know that is him in the 1880 census, I think his age is just off by 5 years. In later census he is listed as 10 years younger than he actually is so I've started to take the ages listed with a grain of salt. I'm just asking if anyone else does this. Even with more recent relatives who should know their birth dates their ages seem to vary 1-5 years in census's.
So if I give his actual age some wiggle room, both census I listed could be him because it matches his most probable birth year 1850/51 but I still have no way of knowing which one is which and now apparently their were two William McNevins running around NYC at the same time, the same age, with two siblings with the same name.