find duplicates in two columns and highlight whole row

Hello I cant seem to find a valid formula to check the data between two columns and high light the row if its a match.

here is my example.


Row 1 column A, Column B,
Row 2 smith,jane doe,john
Row 3 tribet,Jake smith,jane


I would like to verify data from column A to see if there are duplicates in column B and highlight that row if there are. so row two would be highlighted. I have tried different variations of conditional formatting but nothing seems to work. I have tried this formula as example =COUNTIF($A$1:$A$100,A1)>1

any help greatly appreciated.