It's possible, cause she has said things before that only a person who can see would know.
But then they show that the snakes react as if they where a separate will from her own, like in this chap for example.
They did just show now that there is a snake language, so maybe the head snakes simply tell her what they see?
Some hypotheses and limited real-world studies indicate that even humans possibly have dual-consciousness. Specifically, primates have highly developed and differentiated left and right brain hemispheres that are physiologically separated save for the corpus callosum. As opposed to most other types of animals which either have no such distinct hemispheres, more integrated hemispheres, or something else entirely. And the corpus callosum itself appears to be a regulator in that it actually inhibits some neuronal communication between the two hemispheres, rather than being a free-for-all highway of thoughts.
There's no evidence to suggest you actually have dual-consciousness with a functional corpus callosum, or at least, both sides do not seem to be aware of each other's existence or the distinction between each other. This might sound far-fetched, how could you not perceive such a thing? But our conscious perception is already a highly processed and filtered experience, you don't have any point of reference to be able to tell otherwise.
When the corpus callosum is cut however in split-brain patients, some studies have shown that the right hemisphere seems to gain awareness of the 'other' while the left remains oblivious as before. Some people interpret the left hemisphere as being the actual 'you' though it has more to do with the left hemisphere being in charge of speech, and therefore the one able to actually speak, while the right one is like a mute twin in your own body with it's own thoughts.
This leads to strange scenarios where people find one side of their body executing actions or expressing ideas they didn't think of. For example, a test subject's left eye only (right eye covered) is shown a card asking them to pick up a ball of their favorite color. They pick one up, then the person is asked verbally why they picked that up. They either say they don't know, or literally invent a reasoning that has nothing to do with the instruction. They are then asked verbally what their favorite color is...and it's a different color than the ball the left side picked up (aka the right hemisphere).
Can different sections of the brain...or perhaps in this case, multiple brains, communicating information seamlessly with each other, while still retaining certain individual thoughts? Can one of those sections, or one of those brains, be consciously unaware of the actions and thoughts of the other parts, while the reverse is not true? It's not well studied as I said...but there certainly seems to be some merit to the idea.
Big wall of text aside, and I don't think the author was thinking that deep, but I think it's entirely plausible the snakes are totally aware of what she's thinking and execute actions she 'commands' seamlessly as would any other part of her body. But meanwhile, the snakes still retain individual consciousness in which they can essentially keep their own private thoughts from her, or execute their own action.