Just for light relief, I had the opposite problem last year. A returning couple with a 1 year old and a 3 year old wanted cots for both of them!
I did feel it was odd to have a 3 year old sleep in a cot, I must say, but there you go. Fortunately we did have two cots, but it was a bit of a kerfuffle setting them up and it turned out No. 2 didn't have a mattress so we had to buy another one. And I haven't even started on the difficulties with paddling pools and baby-sitters.
They're lovely people, but I just wonder if they have any idea of the problems they caused!
Mols