Japanican overbooking?

I'm in the process of booking hotels for a trip and despite already booking most of them, i found a better one in kyoto for cheaper. The website says they have no availability for my dates, but I was able to find a room on japanican with them for those dates. I'm worried about canceling the bookings I already have and relying on this one to pull through. What's the likelyhood of this being an overbooking and them turning us away?

as a side note: i did email them and they said they have no information regarding the agency website

by No_Tomato_Paste