When same transfer is completed from two end simultaneously we are seeing multiple copy of same file

When same transfer is completed from two end simultaneously we are seeing multiple copy of same file.

1. Create one transfer with 100 files in a folder keeping .auto complete off.
2. Open the same transfer in another browser with different user
3. Click on complete transfer with first user. it goes to pending state
4. Click on complete transfer with second user without refresh
5. In the repository we are seeing same files uploaded twice

Ideally when one transfer is in process we shouldn’t allow any other user to start the same user