Is it okay to publish two novels similar to each other?

With Romance novels people aren't expecting Clic Literature, in fact you can look up formulas on how to write them that go as far as to tell you on page ## have a scene. So, no, I don't think it will matter as long as the background is somewhat different as you have said, one being the 1900's and the other being now. Also, if you pay enough attention to social conventions of the time the story is set, it will be hard for people to see the connection. Lastly, read two Stephen King novels, all of them are just about the same. My favorite thing about Stephen King is that he has called himself a "Sausage Writer" meaning that he will never make fillet mignon, but he makes a good living with sausage.