Is there a tool available to compare two lists? We are looking to dedupe, as well as account matching against two lists at once.
Quick method of doing this would be creating a smart list with two filters inside it "Member of List 1" "Not a Member of List 2". It will resolve your problem upto some extent. Apart from this, we have our own De-dupe product for account matching and for bigger databases. You can contact us at rahulv@grazitti.com for more information on this. We would be happy to help you!
Excel should be able to do this.
Depends where the data is.