Weird shadow effects, unable to reproduce with identical object and same materials.

I’m new to Blender, this is my first attempt at modeling, so I’m sure I’m doing something wrong here. When I render this scene, which is a removed portion of a much larger scene, I get these random shadow effects on some of my surfaces.

Though they both appear to have identical properties, including the same materials applied, one has weird shadow effects while the other does not. When I uncheck “receive” under the Shadow menu in Materials, the effects go away. The But “receive” is checked on the other cube and no effects are present!

The weird effects also go away when I select “Buffer Shadow” or “No Shadow” instead of “Ray Shadow” on my light source.

I’m sure it’s something quick and stupid, anyone care to assist? :slight_smile:

It looks like you might have overlapping faces. Maybe you duplicated your model by mistake.

That was it! I apparently had 15 duplicate faces (one for each story of the building I was modeling) :eek:

Removing them solved the problem. Thanks Morio!