While downloading if you are saying the file in same location with the same name
Ex: Test is the file name, for first time it will save as — Test
for second time it will save as — Test(1)
If you want to save the file in same location it’s better to use with datetime including with file name or
Before saving previous file move to some where else or delete that then save it
It will work
If you want that previous downloaded file before going to download you can move the file from one place to other location then download the download the file & save in the same location.