If User uploads same file is it override or both the files are availble?
Regarding uploading the files which is already there in the Sharepoint,
If you are manually uploading a file in the component which is already exists in the provider end then it will override the existing file and you will be able to see the latest file in the component,
And if you upload a file in the notes and attachments section(Salesforce), with the help of auto export trigger it will export the file and you will be able to see both files and latest file will be in the versioning form,
For more clarity I 'm attaching the recording, Please go through and let us know if you have any questions or concerns we will assist you accordingly,