I have french doors and want the kind of deadbolt that has to be keyed on the interior as well as the exterior. I am confident I can find them as I already have two in place.
Dexter, as well as a number of other brands, have those kinds of deadbolts. They are called Double Cylinder deadbolts. If you do a general search for Double Cylinder Deadbolts, many options will come up. Dexter is one of the more specialized brands for security as well.