Yeah, after 20 years living together, you kind of begin to morph into each other...
Seriously though, did you apply for any credit jointly (anything where you'd have given them both of your SSNs)? If someone got the SSNs mixed up, and pulled (or, more likely, reported with a new account) your credit, but used your husband's name and birthday, it might resister as you using that new name and date. That's the first thing that occurs to me.
