Thanks to HOMYHUB's integration with Siri Shortcuts, you just have to:
1- Create another shortcut.
2- Choose the one with the HOMYHUB App.
3- Choose the action to be "Operate garage door", and there attach the action of Operate door "XXXXX" (Exact name that you have given to your door 1 in the HOMYHUB App) and then another of Operate door "XXXXX" (Exact name that you have given to your door 2 in the HOMYHUB App).
4- Call him, for example: "open all the garage doors".
And that's it! Now just ask Siri whenever you want. 😎
Here is a video attached for reference: https://photos.app.goo.gl/pc6j8Ui1UkHAjXsR6