The Book Switch Theory

[ReneZ]

There are some 1915 and 1918 newspaper reports where the letter is called a 'flyleaf' and some of the names in the letter are quoted.

If indeed those newspapers cite Marci, Barschius, Kircher, or Raphael, that would indeed be evidence that Voynich at least knew the contents of the letter by 1917.   But anyway I already think that it is quite likely that he knew about the letter and its contents well before the 1911 sale.


...

Since, by coincidence, I received another newspaper clip just a few days ago, let me just add this one thing, since it perfectly fits with this point.
The 1918 article has been transcribed partly here (I only took the bits I found interesting): 
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Items from the Marci letter that are named here are Rudolf, Kircher, Ferdinand and the 600 ducats.
BUT!...
As already in 1915, and here still in 1918, he is not talking about 'our' Rudolf II of Bohemia, but about Rudolf I who died in 1291 and was a contemporary of Bacon. Voynich believed that the Rudolf in the Marci letter bought the MS from Bacon for 600 ducats.

He does get Ferdinand III right, but I am especially amused that he mentions Kircher only by his first name: Atanasius. 
Now the Marci letter only includes this first name, and not his family name Kircher.
So was Voynich also confused about who he was?

No, certainly not, because the article includes:

Atanasius, noted astronomer and philosopher of that period, is said to have transliterated the beginning of the book, the study of ciphers being one of his achievements. It was Atanasius who established the famous astronomical observatory in Peking, China, and wrote many books on the Chinese.