[plusbryan]

Having taken a lock picking course, I can say that one lock is approximately the same security as two - even after 15 minutes of instruction, with the right tools I could unlock most any standard house lock in moments.

Home door locks are a deterrent more than anything else, so I'd opt for convenience.

[jeltz]

This is not true everywhere. For example here in Sweden the second lock is usually a lever tumbler lock or some variant thereof. Way harder to pick than pin tumbler locks. What matters is the type of lock, not the number of locks.

[bluetidepro]

Oh, okay. That's actually really interesting, I had no idea. Haha Thanks! :)