Specifically, would there be room within a proportionate humanoid body for a complete duplicate of the circulatory system to grow from birth?

Assume:

• That each branch of this circulatory system needs to distribute whatever's in it to the same bodily tissues that the main circulatory system does.

• That these two circulatory systems pump different fluids, and do not overlap.

• That there's a heart-sized organ at the core of this secondary circulatory system, which is responsible for providing pumping pressure.

• That the genes for this exist, meaning that the body is capable of building this thing.

• That said heart-sized organ can be anywhere within the body that isn't already occupied by another bodily structure - in other words, no re-arranging organs inside this thing.

• That said heart-sized organ does not need to be within proximity to the lungs.

Note that I'm not asking about what evolutionary pressures would lead to such a thing existing, nor am I asking about what a secondary circulatory system could be used for, nor am I asking about what genes would be necessary for this to happen; I'm simply asking whether there's enough physical volume within the human body to do so.