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If the brake pedal's not retracting properly then that can cause dragging brakes as the pressure in the brake line can't be released. In my experience this gets progressively worse, and ends up with the brakes binding completely though. Wouldn't account for the soft pedal - it usually has the opposite result, and you end up with a rock hard pedal, but the brakes jammed on solid.
If it pulls up dead straight it is more likely to be master cylinder related, have the pedals been adjusted? if there is not enough clearance between pedal and master cyl rod the brakes can stick on