If you put the reference number correctly, then no need to worry. Case officer handling your case can already verify it using the reference number. They can also request the scanned document if they feel they need to see it. People including myself attached the IELTS exam together with their education credentials (diploma, TOR, educational assessment such WES/IQAS and IELTS).Yes, I have filled out the details over there so I do not have to upload my IELTS scorecard ?
For your peace of mind, you can also submit a copy of it using webform.