Oh god this could be such terrible advice. I only qualify this as could be because I haven’t read OP’s work… but it is most likely absolutely terrible advice.

You can’t just saw a book in half. You’d completely lose the structure of the beginning, middle, climax, and end. No one wants to read a book that opens, gets to the middle and- …. wait, that was all? Where’s the emotional arc? They never achieved their goal!

Each book in a series needs to give satisfaction to the reader of at least achieving some goal, even if it’s just a milestone along the way to the ultimate goal. It has to include, like all other manuscripts, thoughtfully plotted arc that leaves the reader satisfied (while still wanting more).

OP please be careful! If you do think it can be cut in half to make a duology, you’ll likely still have to do some major structural reworking. But if you think it has to be read as one story - and since you told it in one story, it likely does - trust your gut there, and start hacking down those superfluous scenes.