Red Arrow Indicators on Layout Templates
In the layout template drawer, at the bottom of your design window, you'll see lots of great predesigned templates to choose from. On several, you may see a red arrow in the upper left corner of the spread...this is an indicator that the layout is a result of flipping another layout horizontally or vertically.
You'll see all variations by default, but may select your preference to show/hide these variations at any time by simply 'control' clicking on any layout in the drawer. You will also see where you can delete a particular layout if it's just not one you like or wish to ever use (please use caution before deleting tho :).