I think you're cloning the wrong thing. I think you're choosing what to clone because you want something that has two mesh groups, but the medicine cabinet has one mesh group that is for the glass. Glass is supposed to be reflective. The original package has a PhongAlpha shader applied to the glass. Yours doesn't have the PhongAlpha so I'm guessing you changed it to Phong? There might be more than just the PhongAlpha at play in your cloned package, though I couldn't tell you what it is off the top of my head.
Usually, it's the specular that controls shine. Both the specular and the bump map for the glass mesh group is very small. The bump is 4 X 416 and the specular is 16 X 16. It's as if the specular and bump map for the glass group is not supposed to be doing anything.
You could try making the specular darker in the area of your mesh that is giving you trouble.
If I were you, I would either clone something with one mesh group, such as the decor books, and take your two meshes (the pizza and the box) and join them in Blender and combined the two UV_0 maps into one map.
Or, you can find something with two mesh groups that does not contain glass. Don't do a plant either, because that has transparency built into it. Try to find something that's a decor object and doesn't involve animation. Something that the sim does not interact with. (Though possibly you could change the tuning). If it's something that goes on a wall, and you want your pizza to go on a table. You'll have to change the footprint. There's a tutorial for that here.
I don't know what you could clone at this point but I'll see if I can find something. If I can, I'll get back to you.
Edit: I'm still looking to see if I can find a suitable object to clone. No luck so far. I did, however, notice that you have the pizza the same cut number as the wooden part of the medicine cabinet. In the medicine cabinet package, that cut number (the wooden part of the cabinet) is using the big specular map. The one that is 256 X 256. Try messing with the largest specular map you have in your "pizza test" package. Darken the colors somewhat. Maybe make the whole thing 100% black.
2nd Edit: Yes, definitely try altering the largest specular. Make the whole thing pure black and make the alpha black, as well. If you still have trouble. Post here again.
