If mail merge requires your addresses in multiple parts/cells...

[Benjamin Cowles]

...how do you check for duplicate addresses?

I had been conveniently recording my addresses into one cell in excel, with which I could easily check for duplicates. Now that I've just decided to use mail merge to save some time creating mailers, I have to break my addresses up into street, city, state and zip. I've never set up a duplicate check across groups of cells. 

What do any of you who have this setup do to check for duplicates? Thanks