Was an issue, but I couldn't define adequately the reason. During the booking, I don't remember to have the option to change the age of my kid. I came early and alone to do the check in and receive the key.
When we arrive late in the night, the booking was done for under 1 year old (she is 11) so just one bed was in the bedroom.
They offer option to resolve and that's a good point, but the error could be in the website, or the hotel options.
But definitively, the location was great to visit different and interesting areas of Lugano.