"any person" and "any single person"

What is the difference between them?

Any Person, can be use while referring to one, and same with single. a person many be alone but has a partner while a single is a person that has no partner

There is not a great deal of difference in the usual sense.

The usual phrase is ‘any person’.
Sometimes ‘single’ is added for emphasis of the fact that it apples to all.

Of course, it is possible that the second refers to aany person whi is not married, which is, I believe, what Estherbunga was driving at.