If you are considering quad line kites, the skill sets are mostly distinct. You can learn to fly a quad without learning to fly dual, and you can learn to fly a dual without learning a quad. Quad line kites are generally slower and deliberate, far more precise with the ability to slow, stop, and reverse. Dual line kites have more options including kites with high power or force if you like a workout, kites with extreme speed, and kites capable of amazing acrobatic tricks.
Some skills are transferable like understanding the wind window or understanding how air turbulence affects flight, but mostly you can learn either one in about the same time frame.
With the help of an experienced pilot that can give immediate feedback you can learn basic control in an hour or two. Without an experienced guide you will need experimentation and instructional videos and it will take longer.