This is the typical problem with using generalist catalogs rather than country-specific catalogues.
The Portuguese catalogues, namely the most detailed one (Alberto Gomes) describe 4 types of "X Réis" according to its diameter:
Ø 34.0/35.0 mm..... M2 10.01 to 10.03 ... (KM#470) ... 1835/36/37………… (Flat “3”)
Ø 33.0 mm.............. M2 11.01 to 11.05 ... (KM#470) ... 1835/36/37………… (Flat “3”)
Ø 32.0 mm.............. M2 12.01 to 12.04 ... (KM#406) ... 1836/37/38/39 ……..(Flat “3”)
Ø 31.0 mm.............. M2 13.01 to 13.05 ... (KM#409) ... 1837/38/39 ……….. (Round “3”)
Only the last reference has the "3" with round top.
There are also variations in the size of the legends and legend errors that I have not refered.
In this case, the Krause catalog, instead of clarifying, only added to the confusion.