Note, In this post, I will write “space” to refer specifically to the whole of space, not the every-day definition of space in terms like “a large space”, or “outer space”.
In the transcendental aesthetic, Kant claims that there is only one “space”. When we speak of dividing “space” into multiple spaces, there still remains one all encompassing “space”. The argument seems logical and almost intuitive to me. Usually, space is what we use to separate and distinguish objects. It goes without saying that “space” cannot separate itself. In that sense I agree with Kant that there is only one “space”.
However, I think there is a point to be made for other forms of separation. Primarily, we can separate multiple instances of one object in time. In that sense, you could argue that there is one “space” for every moment in time. Meaning that looking over the whole of time, there are an infinite number of separate “spaces”.
I do have to concede however that this is not how separation is often thought of. Furthermore, Kant has yet to touch on the topic of time, so my views may change.