Copying a handset, and why rolling code cannot be copied

Fixed-code handsets can be cloned in a shop in two minutes. That is convenient, and it is exactly the property rolling code exists to remove.

Two kinds of handset are in use on shutters, and they behave completely differently when you try to duplicate one.

A fixed-code handset sends the same code every time, set by DIP switches or learned from another handset. Duplicating one takes a blank and two minutes: hold the two together, press, and the blank has the code. Convenient — and it means anyone who can capture the transmission, or borrow the handset, has a working key.

A rolling-code handset cannot be duplicated that way, by design. Each press retires the code it just used and issues the next from a very large sequence, and the receiver tracks where in that sequence it is. A captured transmission is already spent. Adding a handset means pairing it at the control box, which requires physical access to the box.

That is the trade, and it is the right one: a handset that can be copied in a shop is a key that can be copied in a shop.