The original Japanese "red wax mono" U.K. version was released in 1982 and limited to 10,000 pressings. Four years later (in 1986)EMI/Odeon reissued this pressing and catalog number to commemorate the 20th Anniversary of the Beatles visit to Japan in 1966. Interestly, all previous releases of Rubber Soul in Japan had been the stereo versions only with different catalog numbers.
The OBI band artwork does not show the "20th Anniversary" labeling, so I assume Mirror Spock used the 1982 edition for tranfer.
Anyway, the transfer to CD has excellent mono sound quality.