L. Rauwolf

[N._N.]

The possibilities are endless.
Widemann may have told Geizkofler who acted as the buyer for Rudolf, and he may not.
If the recipient of the book in Prague - Hans Popp - knew, well, he died within a few months after that.

There may have been a name or names on the then cover, which may have been lost in case it was rebound for Rudolf. Latest when it was rebound by the Jesuits in Rome.

It may even have been widely known when the book arrived in Prague, but nobody bothered to write this down. After all, we are very interested in this, but people then and there may not have cared much who was an earlier owner.

There is certainly a number of possible scenarios, but how many are actually likely? Maybe it makes sense to distinguish between purposeful and accidental obfuscation, although both may have happened simultaneously. In the first case, who else actually had motive and opportunity to do so? The latter option is hard to judge without knowing what the provenance actually was. 

For example, if Widemann had explained he bought the manuscript from some book dealer who could not provide additional information, maybe nobody considered this piece of information particularly noteworthy. This scenario may of course have occured whether Widemann was telling the truth or not. I can also see a scenario with gradual degradation of the information, i. e. Widemann explains he got it from the oriental traveller Rauwolf, the next person in line, not being familiar with Rauwolf, omits the name, the people who hear this information just register 'oriental', and by the time Barschius writes his letter, there are just rumors of oriental origin left.

However, many of the accidental explanations seem less likely to me due to the interest in the manuscript shown by basically everyone involved from Rudolf (demonstrated by the price) to Marci and the number of people in connection to the court who were apparently involved somewhat simultaneously, from Geitzkofler and Popp to Barschius and Marci. Plus, as mentioned, information on provenance getting lost in the Prague era is not necessarily a counter-argument to Widemann providing false information in the first place. That all being said, I would of course not put too much confidence in this whole theory, as it is clearly based on a number of assumptions. Nevertheless, I think the scenario drawn up here is just likely enough to at least be quite suspicous of Widemann and a bit more sceptical of the Rauwolf theory, in relation to all the information we have now or which may be found in the future.