Yes, but don't.
You know Hyosung have a thing about recycling parts, using the same engines for different bikes, using the same fairings and stuff for the 650 as the 125, and basically having as many parts-in-common as absolutely possible. There's a reason they went to the trouble of designing, engineering, and manufacturing the single-disc specific master. It increases necessary torque to apply force while robbing you of feel and lever travel range. You could certainly argue that the difference between the two isn't very large, but with a caliper as blunt and un-precise as the standard TCTC you get on the Hyosung, it still makes it possible and easy to over-brake for the road conditions, grabby at high-speed, and all round a little more worrying to use, detracting from the riding experience.
I had a lot of problems with my brakes in the first couple of years I owned it, and the solution was never to change the master.