I'm a little surprised that no one has asked for this before:
I would like to be able to set multiple triggers for one set of actions. This is particularly relevant for keyboard actions, but could conceivably be useful elsewhere. It seems a bit silly, because i could hypothetically set Trigger A to send the key-shortcuts for Trigger B, but I would rather just be able to set multiple possible triggers for the same action.
The main use case is for a person to be able to trigger a shortcut using both left and right hands. Typically, a shortcut is designed with the intent to use a specific hand or specific position on the keyboard—unfortunately, this makes it hard for the other hand to hit the same shortcut, which might be necessary in situations where the primary hand is occupied (mouse, trackpad, secondary device, etc).
Setting a second trigger for an action-stack avoids having to mirror changes from one set of actions to the other. Configuring a shortcut to send the keystrokes for another shortcut has a similar problem: if the Trigger B shortcut were to change, now the Trigger A actions need to be changed to reflect this.