These aren't particularly valuable even in better condition; with no indication of the host coin's date or mintmark, there's minimal value to a collector, except perhaps a "countermark collector" who just wants a cheap example of these official government counterstamps. The green blotches will also be off-putting to a collector.
The original coins have a few interesting points. Notably, that different provincial mints in Brazil issued the same denomination in different sizes and weights, depending on copper availability, hence the need for the subsequent government counterstamps. The catalogue also notes that the coins were extensively counterfeited, to the extent that modern collectors don't know, or even particularly care, whether a specific coin is counterfeit or not. Both counterfeits and legitimate coins would have received the official government counterstamp and put back into circulation. Given that the counterstamp on this particular coin is not very well worn, I suspect the original coin was quite heavily worn when it was recalled for counterstamping.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis