How Do I Apply An Additional Mesh, So That Both Meshes Show Up?

I have two materials, one that colors the tile red, and one that puts a large "T" onto the tile. The idea is that by combining the two materials (by applying them separately) the tiles will be a lot more scalable for infinite level generation.

However, when I apply both materials to the tile, the "T" one is always on top. The "T" tile is literally only a T, with the background being transparent, so I don't know why the grey is showing up.

How would I be able to make this tile show up with the "T" and the red background?