Russian 1809 pistol: 7 English lines (~17.8 mm).
Russian 1798 pistol: ~17.0 mm.
Wirtgen's description of a 1805 pistol, produced in Sestrorezk: 17,4 mm
Wirtgen's description of a 1813 pistol, produced in Tula: 18,4 mm
Wirtgen's description of a 1814 pistol, produced in Tula: 18 mm
most British pistols: 0.56 inch = 16,51 mm (Wirtgen says: 16,7 mm)
British 1796 heavy cavalry pistol: 0,75 inch = 19,05 mm
Wirtgen's description of a French an IX pistol: 17,1 mm
Danish pistols I don't know.
So probably the Russian pistols in the 8.Ulanen-Regiment were sorted out, as their caliber was "much" bigger than that of the British, French and Danish pistols. A regimental order said that all ammunition should be remade to fit the British pistols, as thus they would fit in the French and Danish pistols as well.
The Russian moulds probably were just kept because there was no order to throw them away ...