return a unique list, removing duplicates based on multiple columns (using formula)

Hi everyone,

I am looking to recreate the "remove duplicates" feature in excel based upon multiple columns of criteria using a formula. My list is always changing, so i'd like to be to get this list dynamically rather than using the remove duplicates feature. I know of a way to do it if i'm only removing duplicates based upon one column, but am at a loss on how to add a second column as an additional criteria.

I've tried the ={INDEX(list,MATCH(0,COUNTIF(A$1:A1,list),0))} approach (which works for one column), and also tried subbing in countifs to add the second column's criteria, but was unable to get it to work.

I've attached a sample book clearly showing what i'm trying to achieve.

Thanks in advance!
David