Check for duplicates

I have a very unique problem and welcome any suggestions. I have 3 identical columns of information. The only difference is each column represents a different time frame. For example, Col #1 represents 8:00 to 9:00, Col #2 represents 9:00 to 10:00 and so on. Each row has a person who must select an item from each column but cannot choose a duplicate item nor duplicate time. Is anyone up for the challenge?
So far I have been checking the list manually. Help!!!!

EG

Hi

Can you give an example? Perhaps a spreadsheet (zipped) to show what you mean and how it would be limited for the data given.


rylo