Signed up for the promo on Dec. 25th and booked a room in the Düsseldorf Hilton an January 3rd. No double points. Called HHonors today (for another reason) and asked about the promo conditions as for the stay mentioned above only the regular points posted.

The agent confirmed that I met the t&c of the promo - he confirmed that the bookings have to be made after the registration, not after the beginning of the promo. It might be that the points posted later and not with the points of the stay. He told me, they expected them to post with the base points but was not sure about this and told me they might post later.

I will wait and see if the points post later (which I doubt)