I am with Dan here a bit. PVDs had a very dubious history when the were first introduced in the mid 60s. Then they were used in pitch and roll not just yaw. The issue of course is whether they are telling you to follow them or oppose them. With two or perhaps three as they were first deployed this clearly confused a lot of us when we tried them.
I can also understand how this might not be a problem with one in yaw as TopBunk suggests.
Indeed I remember a similar issue with the Harrier rudder pedal shakers - only one shook and was that the one you had to push or leave alone? We sorted that out with the 'stamp out vibration' motto.