I have found in my research that there are mistakes made everywhere. My father is listed twice in one of the 1920s directories, once under Guy P... and another time as Guido P... (His birth name), at different addresses. Apparently he moved and got counted again by another enumerator. The same for my grandfather who is listed in the 1890s once by his initials, J. F. Sp... at one address, and another by his middle name, Fred Sp... at a different address in the same area. I found different addresses for grandpa in the Great Registers, some of which contradicted what I found on the directories and even the US Census. I tend to believe the Great Register because he was actually there in person to register, and so the information is more likely to be correct. Sometimes I think the persons who gathered information for the directories and the census were hurried/harried, the people weren't home and they just made notes from what the neighbors said. And sometimes people did move quite often, especially single young men. So you might check the SF Great Registers. If they were citizens, and if they voted, they had to register every two years. Good luck, "rwalker"