According to my source in El Aiaun, some Sahrawi youth are carrying SADR ID cards like the one above as a silent form of protest against the Moroccan occupation. The card Moroccan authorities would rather they carry can be seen here.
They got their cards while living in Tindouf, but eventually returned to Western Sahara after camp life became too hard. My guy in Western Sahara says one person he knows with the card uses it to keep hope for a free Western Sahara, while another plans to use the card to claim SADR citizenship once he reaches Spain.
Obviously, I'm not in Western Sahara to confirm this, but it seems true to me. I worry for the people carrying the cards, though--I don't think Moroccan security forces will be pleased if they find the cards on the youths.