You need to find a brake specialist with a good reputation. The master cylinder is not the common point to the two front brakes, there is no common point unless you consider the brake booster, and that would also affect the rear brakes.
The brake system is an X feed type, meaning that there are two cylinders in the master cylinder, each one feeds one front brake and the opposite side rear brake.
It would be odd for both front brakes to have the same problem at the same time. Do you have ABS and if so, have you tried unplugging the ABS module and test driving the car to see if the brakes start dragging? I don’t really think it is the ABS, but it wouldn’t hurt to try this test anyway. Its the only other common point besides the booster.
Yes, both hoses can have this issue, it just doesn’t seem like it would happen at the same time unless the brake fluid got contaminated some time in the past.
Have you done a complete flush of the brake system?