It is not supported to have multiple audiences in the access token.
You could authorize (could be silent authentication) a second time to use a different audience and as a consequence obtain an access token suitable to another API.
You could also configure Logical API for Multiple APIs. If you have multiple distinct API implementations that are all logically a part of the same API, you can simplify your authorization process by representing them with a single logical API in the Auth0 Dashboard. Doing this allows you to implement just one authorization flow, while still controlling access to the individual APIs by assigning the appropriate scopes.
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