Why legal documents have always had the name of a spouse
It has to do with identifying someone. Even back in 1888, there were a lot of Hezikiah Subukowitzes around, even with the same birthdate. So, spouses were used to differentiate. The chances were awfully slim that there would be two Hezikiah Subukowizes who were both married to a woman named Zelda. It may have happened, but it would have been very, very rare.
Just having a name, even with a birth year, doesn't guarantee that you have identified someone correctly. I share the same name and birth year as the man who is married to Julia Louis-Dreyfus. Of course, I'm not, so you know which Brad Hall you are dealing with.
Of course, today there are lots of other ways to conclusively identify someone, such as social security numbers, fingerprints, DNA. But back in your ancestors day, they had to make do with what worked, and the names of both spouses, with their signatures, was pretty iron-clad.
Posted by Brad Hall