Is there a way to mirror and duplicate in one action?

I have this cube:

When I mirror it around the x-axis I get this:

but I want this, so that the object is mirrored and duplicated:

Currently, I can do that by copy-pasting the cube then mirroring the duplicate cube (leaving the original cube in place), but it feels like there should be a better way.

How do I mirror an object such that it is duplicated, leaving the original in place?

• Use empty and Mirror modifier with that empty set as mirror object. Or Array modifier with that empty set as Offset object. Dec 22, 2015 at 0:03
• Set 3D cursor to the center with [Shift]+[S] and set it as the pivot point with [.] (period key), then use [Shift]+[D] > [S] > [X] > -1. Dec 22, 2015 at 4:21