There is a seller that is selling both the LMD and the MMD 25 ruble silver coins which he personally thinks that the MMD silver coin is more rare. I gave a check in my collection and bingo, looks like I do have the MMD version.
It did make me wonder for a bit as of which is rarer. In 1994, Leningrad Mint did not strike any of the 5 oz silver coins and it did make me a bit doubtful if Leningrad Mint actually struck more of the 5 ounce silver coins back in 1993.
Here is the infomation of the 1993 25 ruble:
http://www.cbr.ru/eng/bank-notes_coins/bas...t_num=5115-0001
Here is the infomation of the 1994 25 ruble:
http://www.cbr.ru/eng/bank-notes_coins/bas...t_num=5115-0002