The name "Finck" originally comes from Austria, meaning Robin has Germanic origins.
Surely the people who misspell "Robin Finck" know that but the abundance of spellings is just too much for them!
As for "Robin", our Robin started to use it in the late 80s or early 90s. His real name is Robert. It is said he decided to be called Robin when he was in drag bands. As the name "Robin" is both masculine and feminine this is understandable.