Sometime the device has been installed at a high place or inside a fixed enclosure. People has to climb high or open the enclosure to press the LEARNING button which takes a lot time when a new transmitter needs to be programmed.
1,Press button 1 and 2 at the same of the programmed transmitter
2,Press button 2 again after step 1 on the same transmitter
3,Receiver/Controller enters learning process and waiting for new transmitter
It makes the whole process more convenient.