Rorogio,
I sent them this morning an email (at address
kindleuser@duokan.com) where I wrote about the problem with CE encoding in some ebooks in pdf formats and attached this particular ebook which is not shown correctly by Duokan OS.
I will report here on this thread if/when I get some feedback.
You could write to them using the above mentioned email address, because this is the only way to speed them up.