My early 700b has the -20 db setting on the left. My later 700 WOPL from Glen has the newer style faceplate with -20 db on the right.
In either case the -20 db position requires closed contacts to short out/bypass the 22k resistor which then results in higher meter current at a given output level. Otherwise, open contacts for the 0db position.
Because of this labeling difference the early faceplate requires an On/Off contact arrangement vs the later faceplate which requires an Off/On contact arrangement which was/is probably more common. Both switches are double pole single throw.
I hope this helps resolve questions about the meter switch functional difference!