The stone is extremely weathered. This due to its orientation. Nevertheless one still can see the fragments of the inscription by having a close look at the picture.
I can just barely make out parts of the "1861", though not the "22 MI" that sits above this on the stone at Le Bezu, so one would have to take this on faith. If, as you say below, this calvaire or marker, does not appear on an IGN map, and is not referred to in other texts, then I presume it was a close inspection of the stone itself that led you to the conclusion that the inscriptions on the two stones are the same. One might also wonder if the calvaire above also bears the INRI inscription on the cross part, as per the one at Bezu.
Anyone remember the Bezu calvaire/cross we lately discussed in Richard's thread?
22 MI 1861.
By solving this inscription one will arrive at the point shown on the picture below: a twin calvaire/stone cross that is not mentioned on any map or any webpage.
By examining this cross or better said marker, one will notice that it has the same inscription as the one we started from....22 MI 1861. And by combining the 2 twin calvaires and by using againg the 22 MI 1861 one will arrive at the third marker.
Obviously, you don't want to say where this second stone is, but can I ask, please, did you find it by solving the clue in the Bezu inscription, or did you find it by some other means, and then subsequently make the connection back to Bezu? If there is a third marker, then one might have a triangle-shape enclosing a particular area. The alignments of the Bezu stone are interesting, even without the location of the second stone to work from.
Looking back at the Bezu thread, and your contention that the "M" is not really an "M", it does seem on one of the close-ups that the M is formed by two shapes, a bit like two inverted ticks, or inverted square root signs, that cross each other that their ends. That's as far as I got with that.
I'm still looking at the landscape aspects, and the idea of these and other stones being connected in their placement; of something encoded in stone and scattered about the landscape; so this is all interesting, if a little bit frustrating at times. Your posts are the principal reason I stay here, btw.
I'm not saying there's a specific connection, but thinking of these stones makes me think of this passage from the Necronomicon, quoted by Michel Lamy in his book on Jules Verne.
To construct the porch through which will manifest those who come from the void, you must erect stones in certain configurations. First you will place the four cardinal stones that will define the direction of the four winds that blow according to the season. Toward the north, place the stone of the great chills that will be the gate of the winter wind, and you will carve there the emblem of the bull, sign of earth ..... These stones will be the gate by which you will invoke those who are outside the time and space of men. Pray on these stones at night when the light of the moon grows weak, turning your face in the direction from which they will come, by uttering the words and making the gestures that will bring the Old Ones and allow them once again to walk the Earth.