The line perforation 10 1/2 is the most common but some others are exist between 9 and 11 also mixed.
The two-headed eagle in the overprint is yellowish brown.
The first revenue serie from 20-06-1868 was overprinted by brown color two-headed eagle!
STEMPEL-MARKEN sheet watermark, twice per sheet
Forbin catalog lists these revenue stamps under Croatia, page 192.