How to find duplicates across multiple worksheets on a mac

I have this file that has over 100 entries in each column across multiple sheets. Is there a easy way to find duplicates across these sheets? Some of these columns have accounts listed twice within them but I am looking to to compare these sheets and quickly identify the duplicates.  I tried conditional formatting but all it does is finds duplicates within a column not across sheets. I attached a rough sample of what it might look like.