Darren
We have noticed that a small number of people are experiencing an issue, where they join another quick race after they leave a quick race lobby and previously doing a race.
I am investigating these reports today and hope to come up with a solution.
I do want to state that if you receive an invite you will in no way join that lobby until you click on the link and go to that URL.
If you are concerned that you are going to be running extra races erroneously then for now, maybe avoid doing quick races until I have been able to resolve the issue.