This question is more tricky than it might seem at first sight.
I agree that the MS shows no signs of being on re-used parchment. It has been checked under a microscope on several occasions, but I doubt that every single sheet has been checked this way. Manuscripts that have a mixture of unused and re-used parchment also exist.
Certainly a leading expert on this question is Abigail Quandt:
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She said (referring specifically to the Voynich MS) that detecting palimpsests can be difficult. That multi-spectral imaging is more reliable than just microscopic investigation.
Again, there has been no sign of earlier use of the parchment from the multi-spectral imaging that has been done in 2014, but I have no real report of that.
In the end, this is not a question that can be settled by a popular vote, I am afraid.
However, it is almost certainly true (FWIW).