Hi @Raki ,
Currently, there is no OOB method to add today's date to the file name during upload processing.
As a workaround, we could use "Send a http request to SharePoint" action in flow to rename the file after the file has been uploaded successfully.
Simple test for your reference:
After completing the flow, file name will show like this:
Please note that the action executed in the Flow for the files in SharePoint will change the version of the file, and the Modified user is determined according to the account of the connection configured on the action.
Since we cannot change the file name when uploading files, there will be no duplicate files because duplicate files will not be uploaded successfully.
Similar issue for your reference:
https://powerusers.microsoft.com/t5/Building-Flows/Renaming-a-File-in-SharePoint-Online/td-p/176708
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