If you're able to send a paper application ASAP using the same payment receipt, and if the AOR for paper is faster than online ones, CPC Sydney will open your paper application first, send AOR for it. And by the time they open your online application, it will be "returned" because of invalid payment receipt, failing completeness check.
Your receipt is like a cheque, once Sydney CPC 'cashed' it to an application, it cannot be used for another one.