Excel Formula need help searching, multiple entries-???

Obviously this is just an example. I have a huge list of at least 2,ooo entries with nothing but record numbers and billing codes. These record numbers are associated with a specific billing code. I want to find multiple record numbers per billing code and add them to the list on the right (in the green). I performed a vlookup but it will only give me one entry not the other 5 entries under that specific billing code name.
Any advise will be helpful.

Thank you,

Please see sample-