Compare 2 lists in different colums

I keep up with attendance at my job. In column A, I have the entire roster of our employees, by last name only. In column B I copy and paste the names from the Swipe Report (which shows what employees were present that day). For privacy reasons I'm making up names instead of using their actual names. The spreadsheet looks like this:

Last Name Last Name, First Name

Arthur Arthur Clint
Beaumont Beaumont Jason
Johnson Johnson Derrick
Klein Klein Mitch
Larson Larson Silvia
Mathews Mathews Carl
Person Smith Terry
Smith

Basically what I'm trying to do is find out which name(s) in column A that aren't in column B. (In this example, obviously "Person" isn't listed in column B) but I have a huge list of names so it would take forever for me to go in and search individually. I've tried everything I've found on the internet and none of it has worked.

When I did that, it just left the cell blank

Okay once I did the trim and clean functions, it worked! Now my only problem is we have a few people with the same last name

I think what we're going to do is in the Swipe Report, each employee has a badge number. We're going to get our IT people to incorporate those badge numbers into the roster, that way I'll be able to use that same function, without having to deal with names. So it would be like FON12345, etc. I appreciate all of your help though!