How to copy objects in Blender without copying their materials? Need to copy objects from one layer to another in the same scene, but sometimes also one scene to another.  

I use Ctrl + C and Ctrl + V for this a lot, but problem is now there are 5 copies of around 20 materials.  

EG:  Material1, Material1.001, Material1.002, Material1.003, Material1.004, etc

Another post said to duplicate the objects instead, then move them to another layer.  But couldn't see how to do that for scenes, and prefer using Ctrl + C/V. Is there a setting or way to stop copying the materials but still copy objects using that method.

Don't want to link the objects either.  Want unique, standalone copies of the objects.  But only one instance of each material.
To copy objects without copying materials create linked duplicate of all adjacent objects; they will use the same material (along with other data). Then in order to make linked objects independent from each other (sharing only material), make them single-user via Object > Make Single User menu (or press U while in 3D Viewport) and choose Object &amp; Data.

You can do the same between different scenes by linking them to that scene; press Ctrl+L and in Objects To Scene dropdown choose scene to link them to.
Make sure to make them single-user after linking if you want them as independent objects.