I don't think there is anyway to guarantee the type of room you will get. You can make the reservation, add a note in the preferences requesting the double beds. Sometimes calling the hotel direct will help too. If you check in early and no rooms are ready like that, ask the front desk if one will be available a little later and if you would wait for that one. Most front desks that I have seen really try to accomodate their guests. Sorry this isn't of more help.