avoid repetitions in excel

[aosewa]

I am currently updating an excel worksheet created earlier on by
someone else, How can I ensure EXCEL checks for any previous occurence
of the rows similar to my new updates so I do not populate the
worksheet with redundant repetitions ?

 

[Mike]

How is a macro going to understand the concept of "similar"?
As a workaround, maybe adding a keyword column and bubblesort it.