Play 2.1: multiple colorized materials with the same base texture image not exported correctly
Create TWO new materials. Use color sliders to assign the color red to one, blue to the other. Name each material after the color. Assign the same texture image (I used the SketchUV default texture "texture_grid.png") to each. Tick the "colorize" box.
Apply each material a box using triple click to apply to all surfaces.
Export model to Unity using PlayUp tools 21.0
Unity materials folder contains one material named "texturegrid" colored blue. The red material has not been exported because PlayUp tries to name both of them after the texture file ("texturegrid"), instead of the material name ("Blue" and "Red" in this case), and there is a name collision. http://i.imgur.com/JPFKEFl.png
Unity texture folder contains a colorized blue textured version of "texturegrid.png" named "texturegrid.tga", but no read texture for the same reason as 5 above. http://i.imgur.com/VS1CTnA.png
Solution: PlayUp texture exporter should name colorized textures and materials after the unique Sketchup Material name, not the Texture Image.