This is from the French catalogue Yvert & Tellier :

Overprint "REPUBLICA" (1910): For the 10reis says that the overprint is red (rouge) and in parenthesis says it's greenish (verte) to the 20reis
When overprint/surcharges color is not mentioned it means that this is black.
In 1911 - overprinted ASSISTENCIA: 10r. surch. red (R) and 20r. surch. is black (because color is not mentioned)