Hi-lite rows with at least 2 matching columns

Hello,

I've tried lots of searches but keep getting answers for rows that match exactly. I need the opposite. I have a spreadsheet with 3000 rows. Here's an example:

Smith Joe 123 valencia joe@yahoo.com
Gates Sam 335 road gate@gmail.com
Smith Joe 122 valencia joe@yahoo.com
Arbor Ann 13 shirley st aarbor@msn.com
Smith Jo 123 valencia jo@yahoo.com


Is there anyway to highlight rows based on at least 2 matching columns? I'm entering data based on handwritten notecards and sometimes it's difficult to read people's writing. As you see above, all the Joe Smith rows are the same person..but because his handwriting is difficult to read I've interpreted it differently each time.

Once I get all the matching rows highlighted, I'll be able to deduce which are correct and which were entered incorrectly. So far I've been using a conditional formula to show all the matching email's and go from there...but those can be hard to decipher and I may not have written it the same way for each entry.

Thanks for any help.