1st page:
skupinacalypso.com/index.php/novice
2ns page:
skupinacalypso.com/index.php/novice?start=2
subcategory page:
skupinacalypso.com/index.php/novice/itemlist/category/19-mediji

Whats wrong? Any idea why 2nd page and subcategory puts everything in 1 column?

Hello,

This happens because one (or more) of your items displayed on page 2 has a starting 'div' before the 'readmore' break which closes after the 'readmore' break.

So, your html on sencond page produces a starting div (of that item) with no end and every element in the page is implemented there because the closing div of the main column is used to close the broken div and entire second col is now inside the first.

What you have to do:

Note somewhere the items showed on page 2, edit them and toggle the editor to view the html output to find the broken div.