It is the toughest decision on all new collectors. But when you learn where to look on the devices and where not to look, that helps also. A double die should show enlargement of the devices. Even on the single squeeze dies there is a distortion on the these as well. But if you find yourself looking at the outside edges of devices, that is a waste of time. That is where you will always find
Machine Doubling, and never a doubled die. The doubled dies are seen on the center areas of the devices, or reduction of devices on incuse devices.

Note on the top image, the devices are enlarged by
Machine Doubling. But note the lower area, the doubled die is seen as reduced sizes of devices on incuse devices.
Note how this is true on raised devices:

But also keep in mind, that
Machine Doubling can affect doubled dies as well. The machine alters the strike after the it is finished.

Note the spread on all of these date devices? Then note the yellow arrows? That is the
Machine Doubling in a single direction of the doubled die.