Hello EVELINE.SA
The Saver Day Pass is valid for the entire Swiss public transport network on its date of validity. So, you do not need multiple tickets, one Saver Day Pass per person/day is sufficient to travel throughout our country for a day. A Saver Day Pass makes sense if the total cost of single point-to-point tickets is higher than a Saver Day Pass, provided its availability.
In addition to your Saver Day Pass, you were supposed to purchase a seat reservation for the Glacier Express, not another ticket.
A seat reservation and a ticket are two different things in our country, a ticket does not automatically include a seat booking; to ride on our Swiss trains, you simply need a ticket, the seat reservation is completely optional, with the only exception of Glacier Express, there you need a ticket (your Saver Day Pass), and a mandatory seat reservation.
Our trains are mass transit, like riding a bus in other cities: check the departure time of the next service, hop on, take an available seat that is left, have a ride, hop off - done.
When you go on rhb.ch to our purchase tickets, you will simply end up at the SBB ticketshop.
For Glacier Express seat reservations, however, go to the Glacier Express website and purchase a Seat reservation only. If they ask you to declare the ticket type (for statistics), and they do not give the option to select the Saver Day Pass, then select the ‘GA Travel Card’ out of the list of options.
https://shop.glacierexpress.ch/gex_en
If I understand you correctly, you now hold 2 Saver Day Passes for the same person and travel date. If so, ask for a refund of one of the two passes. Remember for which one you requested a refund and use the other one for your travel. There is a CHF 10 admin fee per request. The acceptance of your refund request lies with SBB, there is no guarantee given in my reply.
https://www.sbb.ch/en/help-and-contact/refunds-compensation/refunds-compensation/refund-form.html
Kind regards,
Roland