BrendA diazo Plone theme has special text style that allows dividing page main content area into 2 columns.
To do that, create a normal Plone page with necessary styles.
On the edit form - point to the paragraph that will be divided into 2 columns. From Style menu select doubleColumn style.
As a result, the paragraph will be divided into 2 columns. In case you want the whole page to be presented in 2 columns - navigate to HTML source view.
Edit existing HTML code: leave <div class="doubleColumn"> at the beginning of the page and move closing tag </div> to the end of the page.
Save changes.