Very rare for undergrads.
In the UK it is standard - my institution has blind marking, double marking and scrutiny by external examiners for all undergraduate exams. Blind marking: we only have a candidate number and not a student's name. Second marking: someone else evaluates the marks (grades) I give - in some cases independently; external examiner: someone from another institution checks that the marking criteria is being followed.
Blind marking could be circumvented in various ways, but doing so would be risky as the exams will be seen by others. Second marking and external...
Another month, another rationality quotes thread. The rules are: