Yes they state it on their website i believe
Its a hit and miss as the last time I spent a couple of nights there I was charged for one and not the other fwiw
Guess it depends on who is at the desk

There IS an overnight fee but no chica fee per se
I normally don't stay in hotels but needed a place a few months back and was surprised when on the second night there a guy asked if the girl i was with would be staying the night and hit me for the extra $10
If you try to book on the site or hotels.com etc and state two adults the rate changes
As far as the breakfast its decent, not bread and coffee like some places...
The food there is actually quite good albeit a tad expensive

I'll be there in Feb and will definitely post something regarding a chica fee. Have not experienced what LAdiablo experienced, but then again booked single and never brought back a lady to the Dunn Inn for a TLN. The only thing the night staff ever asked for was an id for the chica and always called the room when she was leaving/getting her id back.

The DI has certainly changed since the days of Boyd and then Guy. I only stayed there this time because my wing had to book the DI for certain reasons I cannot disclose here. I usually stay with my favorita in Escazu at the Wyndham Garden Hotel, but of course that is situational to what I do these days. But the DI is not that great anymore in many respects.