Thanks for the info, I have see Edward IV pennies that are Durham mint with an extra pellet but I do not know why
The Bishoprics in Durham and York had the coining right from the era of Edward I on up to HVIII or so. Usually their coins had either an extra pellet or an annulet( basically an O in the pellets) to denote that they were struck by ecclesiastical authorities.
I am going to dig out my old Seaby so I can validate that. The big problem is the clipping removed so much of the legend that you have to go more with known portrait types going from most common on down to the downright scarce.