I am exporting a PDF with the pages set to spreads. My coworker has been exporting a version of the file that shows a line between the pages directly from Indesign. Is there a setting where this occurs? I do not understand where the lines are coming from as there are no lines on a layer in the indesign file.
Are you sure? It is impossible to get this directly from InDesign (at least, natively). Or this line is on a hidden layer. Maybe your coworker uses a third-party plugin or a script?
Are you sure the coworker is exporting spreads and not pages with the intial view set to Two-Up Continious (Cover Page)?:
In Acrobat the pages are viewed as spreads:
Export using a two up layout generates readers spreads with a visible line between pages
Just remembered CS6’s Export doesn’t let you set the intial view as spreads. You can do it from Acrobat.