PDF pagebreaks turn to blank lines in mobi

Hi, there. I am new to the forum, but a bit experienced in converting things in Calibre.

I know that PDF is a bad format and yadda yadda, but sometimes the only source one have is in pdf, so...

I've noticed that when converting from PDF to mobi the PDF's page breaks become blank lines in mobi, even if the option to "delete blank lines between paragraphs" is turned on. This way, even if the text is all right and fluid, there is some blank lines that coincide with the PDF's page breaks.

Is this a feature or a bug? Or am I missing something?

OBS: The PDF document I am talking about is a pure text document, without fancy formatting or images.

Thanks a lot!