It looks like the same "M" as in the word "Mercier" on the other fork. I'd guess they just had different fork crowns at different times. It could be a replacement from a different Mercier frame, but I'd suspect it's original.
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1964 JRJ (Bob Jackson), 1973 Wes Mason, 1974 Raleigh Gran Sport, 1986 Schwinn High Sierra, 2000ish Colian (Colin Laing), 2011 Dick Chafe, 2013 Velo Orange Pass Hunter