Strange date follis

[Byzantofil]

I bring to your attention a strange follis. It is not clear whether it is imperial mint or a high-quality Arab-Byzantine imitation.
And if it's not an imitation, then who does this follis belong to. Consider the options:

1. Heracleus with his son, type Sear 810. In general, it's looks like similar. But there are questions: what is this strange date with ? I have never seen such variant. Where are the letters XX...? And what kind of legs  are visible on the obverse? Is one Sear 810 follis minted over another follis of the same type?

2. Constant II with Constantine IV, type Sear 1010. In this case, there are questions: why is there a monogram Ro instead of K above the letter M? Again — what a strange date instead of the XЧ and XЧI prescribed for this type?

[Joe Sermarini]

I don't have an answer, but it is a very interesting coin.

[Kevin P]

This is Sear 810 with Heraclian Monogram 25 over the M (listed in MIBE as 164c). This variety is known for RY 23, 24, and 25. Your coin looks like RY 23 or 24.  The typical date arrangement would be X / X / II / I(I).  You can clearly see the first X, space for the second X (with a delta in the way), the II after where the second X should be, and the last I (RY 23) or II (RY 24) to the right of exergue line.  The extra design elements you see are from an earlier strike.

As is typical with Herclian bronzes, this coin was struck over an earlier type.  The delta you see where the second X belongs is from an earlier type - perhaps the officina mark. One clear sign of this is there are also remnants of the earlier type on the opposite side of that same place on the planchet - to the right of Heralius Constantine (where you have identified odd marks in yellow).