I solved this by myself.
I modified file /etc/apt/sources.list.d/debian.list - removed duplicate entries:
========= SCRAPER REMOVED AN EMBEDDED LINK HERE =========== url was:"https://s19.postimg.org/m31o1zg03/sources_list_debian.png" linktext was:"https://s19.postimg.org/m31o1zg03/sourc ... debian.png" ====================================
Then I deleted folder /var/lib/apt/lists, rebooted PC and after reboot performed sudo apt-get update && sudo apt-get dist-upgrade.
Now everything is OK __{{emoticon}}__