I'm not advising you, I can only say what I would do: reschedule the shop you cannot report. Yes, you will be out of pocket.
E-mail the help desk, tell them what you did, ask them to CANCEL the shop that you reported, or if they possibly can, reschedule it to you.
Yes, you will be out of pocket
I do believe if you submit the second report, BOTH will be invalidated.
However, I believe this is exacty what a professional would do: apologize, and do your best to "make it right".
Do come back and let us know how it all turned out.
Good luck.