Reverse die m is another of the O/O over-punch mint mark coins that can be determined by the placement of the secondary mark.  However, the pairing with a die 1 on the obverse can be deceiving.

The die 1 is quite distinctive because of some over-polishing of the die at some point in its life.  The over-polishing is most clearly seen in the left wreath where various details are just gone.

In the eagle's right wing there is a loss of feather detail on the outside row of feathers.  We have seen examples with much less detail than the example shown here.

(You can see the coins in our collection by clicking on the VAM link below.)