Need Help Extracting Unique Values Based on Another Cell Value

I am looking for help extracting unique values based on the value that is in the cell next to it.

Screenshot.jpg

In the screenshot, I have a Source Name in Column A and a Plan Name in Column B. What I am looking for is a formula that will give me the same information in column B if column A and B are both unique; i.e. if column A has Source 1 listed twice and column B has Plan 1 listed twice , then column C will show "Plan 1" for the first occurrence of this combination and return a blank for any subsequent occurrence. The main thing is the formula blank if the Column A/ B combination is duplicated.

thanks in advance for the help.

rgds,
rb

Why not just remove the duplicates?

kersplash,

I need all of the data so I cannot delete the duplicates. I would also consider a manual copy / paste but the actual file I am working with is about 36k rows.

Thank you AliGW. It works!