When you walk around a Modular Machinery structure, all of the textures on each side use the basic orange variant at first, then flash to the correct variant once you walk far enough.

Minecraft 1.12.2, Forge 14.23.0.2512, Modular Machinery 1.6.4

Yea, cause they're all overlays over normal blocks. i can't render them differently or you get Z-Fighting.