You may have several Mountain Access Cards attached to your profile, however only one can be used per day. The card that you first scan on any given day will be your new active card; you cannot have multiple cards in use simultaneously on the same day.
To check the Mountain Access Card/s that are linked to your account, please sign in here, select "Mountain Access Cards" followed by the "Mountain Access Cards" tab. This will display the 5 most recently used Mountain Access Cards attached to your account including the card that is currently active.
Do you have a card number that is not displayed in your account? Please contact the Epic Australia Pass team here for assistance.