B2 was issued on June 7, 2002 when the first class rate was 0.34 with a surcharge of 0.11 (sale price of 0.45)
On June 30, 2002, the first class rate increased to 0.37, as did the face value of B2
The surcharge was reduced to 0.08 to keep the sale price at 0.45
B2 retains its postal value of 0.37 when affixed to a mail piece as you found in the USPS listing.
Yes, they were used by many. Here is one cropped from a full envelope during the 0.37 rate period.
The challenge is to find a solo use at the 0.34 rate between June 7-29, 2002.
The B1 breast cancer semi-postal has the most complex rate + surcharge structure having been available for over 20 years. Try to find solo use during each rate period!