This below has been suggested by some, not sure if there are any exact dates available?
Part No. CZH657 Silver on Blue (Embossed) stick-on badge was used between 1969 and 1971. It was stuck to both A-panels.
Part No. CZH2717 Blue on Silver (Printed Flat) two pin fixing badge was used between 1972 and 1975. Later it changed to only being fitted on the left side A panel. There is an August 1975 dated BL brochure that shows Mini's with badges on the left and no badges on the right side.
The dates sound about right to me but the smooth printed badge was the earlier version and the embossed one the later version.
My 72 originally had the embossed badge on the n/s only.
I've fitted the incorrect smooth badge to both a panels as I prefer the smooth version.