Dealing with Duplicate data

I am uploading a csv of prices to my database on a quarterly basis, that then has to be approved by an administrator. Prices in the CSV maybe the same as last quarter or they maybe different. What I would like to do, is when the file is uploaded I would like to check the data and automatically save the prices that are the same as last quarter and display the prices that are different for approval. The prices that are the same can either be saved, or the new version deleted with an updated validity date range save to the original file.
Hopefully that is clear, happy to chat with anyone who can help.