You can get a Weekend Vrij subscription with the supplement for discount during off-peak hours. It's even cheaper than having both subscriptions separately:
 

I would like to know how long it takes for the card to arrive, since I ordered it a week ago and it still hasn't arrived, on the other hand, I would like to know if I can have two subscriptions at the same time?

Good afternoon Valentina Sarmiento. The official delivery time for a new OV-chipcard is stated at 7 days, although unfortunately it can be delayed. If you ordered a subscription that's already started which you now cannot use, please contact our Customer Service (Chat, Twitter, Facebook or by phone).

No, it is not possible to have two subscriptions active on the same card. It's possible to add the 40% discount in off-peak hours to a Weekend Vrij subscription, but this is done via a supplement as explained by Tochjo, not by having both Weekend Vrij and Dal Voordeel active on the same card.

It is possible to have two subscriptions at the same time on different cards, though. This could be useful, for example, if someone needs Traject Vrij to travel from and to work on weekdays, and Weekend Vrij for unlimited travel during weekends.