Uploading a CSV to Clay: How to Remove Duplicates and Filter Sources

I have built a list in Clay and now also have a CSV file that I would like to upload into the same table where the list was created. Before proceeding, I would like to check for any duplicates in the table and remove them if found. Once the duplicates are handled, I plan to enrich the leads. How can I upload a list into the same table and identify duplicate entries within it? Additionally, I would like guidance on editing the "People Source" to apply more filters. Could you please provide detailed steps or best practices to achieve this?