It's like the resumes you come across where the person says they know "C/C++", but doesn't really know anything beyond the very basics of either.
There was a time in the past were it made sense though. Lots of C++ shops had just recently moved to C++ for new projects but still had plenty of existing code written in C.
Why would the recruiter ever know much about technical details?
They should have said the person who gave the requirements to the recruiter.
Internal recruiters often change what they're given. Changing C++ to C/C++ is a real thing that happened to a job my team was hiring for.