True/False to display with a duplicate entry

Hi Everyone,

I'm using excel 2013 and wanted to have a column highlight 'True' or 'False if I receive a duplicate entry. Basically I have data from the previous week (part no's) listed in a column, for arguments sake lets say from B2 to B30. The following week I scan part no's in again in another column, again lets say D2 to D30. In a weekly check I am checking for duplicates, any that come up as 'False' will be ones that have turned up and not scanned on the previous weeks audit. In terms of the true/false I would be looking for this display in the A column (A2 to A30). Any ideas?

Hope this makes sense!

Thanks for any help.