Is MemberInfo (and its implementations) considered singleton?

I am generating a dictionary of mappings to a target object using Expression tree logic and a fluent API.

I would like to ensure that if duplicate mappings are made (for whatever reason) I can either throw or warn at runtime. Is it safe to say that MemberInfo and its derivatives are unique, and singletons to the derived member?

For arguments sake, I am only targeting publicly writable properties at this stage.