Preview cannot display two different eps files with the same name simultaneously
You might want to use and Open two instances of Preview at once.


  Unfortunately, Preview (like most Mac OS X applications) lets you have
  just one instance of a file open at a time. But there’s a way around
  that restriction.
  
  The open command line program accepts a parameter -n that allows it to
  launch the application again, even if it’s already running. So, if
  you’re currently viewing file.pdf in Preview, enter open -n file.pdf
  in Terminal. (You’ll need to supply the full and complete path to the
  file, of course; the easiest way to do that is to type in open -n,
  then drag the file from the Finder to the Terminal command line.)
  Another instance of Preview will launch, complete with its own Dock
  icon, with the PDF document open.