Your comments

I'm sorry I already found a workaround -- I needed to create two references and give them a different name so that they don't have the same name (as they generically do when creating a reference) and then it works. However this solution seems a bit impractical - I may also need to have a Winner FK and Loser FK (for which it isn't really necessary to say they are foreign keys for Teams) - but if I wanted to make them FK, I would need to add 2 more references to do this.