Short link errors

Hi, epicdevspace. Thanks for answer.

I tried to use <?php echo wp_get_shortlink(get_the_ID()); ?> but it’s the same result 🙁

My Common Settings of Permalinks now is : Post name http://www.uzyn.com.ua/sample-post/
I use it for better reading, but because some times I can change URL name – inside the site I use shortlinks (as I understand they a unique & stable).

Need I check permalinks in other way?

For example, this 2 pages have same ID & I don`t know why. You can see ID (shortlink) in footer (down of page / last text line)
http://www.uzyn.com.ua/category/афіша/
http://www.uzyn.com.ua/201508-open-pharmacy/
it`s ?p=11664