A rouble (in both silver and gold version) with imperial eagle grinded flat and tsar nicholas face stamped with "Deposition of House Romanov, march 1917" stamp. However i didn't found how exactly those coins came to be.
I suspect the eagle wasn't specifically ground flat; hammering the punch of the new design would squeeze the coin and damage the reverse design.
Counter-punching coins like that was common in colonies where "official" coins weren't available or traded at a nonstandard rate. You might see, for example, Spanish colonial silver punched over to identify it for use in English or Dutch colonies.
In some cases, they'd use a full-design punch and only a small amount of the original can be seen (like the Bank of England 1804 five-shilling "dollar" struck atop Spanish 8-real coins)
A second variant is the "chopmark"-- a small punch addes by private merchants and assayers to indicate the coin was good. Often seen on US/UK/Japanese "trade dollars" and Mexican 8 real/peso coins sent to China in the late 1800s, and some coins used in North Africa.
I wonder if this is either of these use cases-- "it's clearly good silver, we liberated it from the oppressors!" or "we'll bootstrap our new economy by only circulating re-stamped coins", or more meant as souvenirs.
I wonder if this is either of these use cases-- “it’s clearly good silver, we liberated it from the oppressors!” or “we’ll bootstrap our new economy by only circulating re-stamped coins”, or more meant as souvenirs.
I read both versions of it. I suspect, and what you wrote about eagle being flattened fits, that it was the first and second case but small numbers of it suggest it was made between the 1917 revolutions, as RFSFR didn't issued any coins until war communism was over and in the time issues paper banknotes (and during the period specifically referred to it as "medium of exchange"). But i also read the version that it was only a short series because it was intended as souvenir, which is also probable.
Expensive custom tokens
Writing with a permanent marker over the faces of 
presidents
I seen one more fun defaced coin:
A rouble (in both silver and gold version) with imperial eagle grinded flat and tsar nicholas face stamped with "Deposition of House Romanov, march 1917" stamp. However i didn't found how exactly those coins came to be.
I suspect the eagle wasn't specifically ground flat; hammering the punch of the new design would squeeze the coin and damage the reverse design.
Counter-punching coins like that was common in colonies where "official" coins weren't available or traded at a nonstandard rate. You might see, for example, Spanish colonial silver punched over to identify it for use in English or Dutch colonies.
In some cases, they'd use a full-design punch and only a small amount of the original can be seen (like the Bank of England 1804 five-shilling "dollar" struck atop Spanish 8-real coins)
A second variant is the "chopmark"-- a small punch addes by private merchants and assayers to indicate the coin was good. Often seen on US/UK/Japanese "trade dollars" and Mexican 8 real/peso coins sent to China in the late 1800s, and some coins used in North Africa.
I wonder if this is either of these use cases-- "it's clearly good silver, we liberated it from the oppressors!" or "we'll bootstrap our new economy by only circulating re-stamped coins", or more meant as souvenirs.
I read both versions of it. I suspect, and what you wrote about eagle being flattened fits, that it was the first and second case but small numbers of it suggest it was made between the 1917 revolutions, as RFSFR didn't issued any coins until war communism was over and in the time issues paper banknotes (and during the period specifically referred to it as "medium of exchange"). But i also read the version that it was only a short series because it was intended as souvenir, which is also probable.