Mangas sent to kindle get duplicated

[Incandenza]

First of all, I don't know is this is the right subforum to ask this, so if it is not i'd like to ask the moderators to move this thread to the right one.

I've always sideloaded mangas onto my kindle through Send to Kindle, unless when their size surpassed 50mb. I keep on the cloud some particular volumes or chapters that I want to reread later. The problem is that I can't do this anymore because Amazon creates a duplicate entry for the mangas sent that way: one copy gets to the device as if I've sent it unticking "Archive document on your Kindle library" and another copy stays on the cloud. If I delete the offline copy and try to download the cloud one, it starts downloading but never finishes.

The mangas sent with "Archive document on your Kindle library" unticked remain behaving as expected. Also, I don't have this problem with other kinds of files (doc, pdf etc).

Sorry for the bad English, it is not my native language.