foreach (Renderer r in renderers) {

    for (int n=0; n<r.sharedMaterials.Length; ++n)
    {
        Material originalMaterial = r.sharedMaterials[n];

        if (!materialNames.Contains(originalMaterial.name))
        {
            Material clonedMaterial = r.material;
            materialNames.Add(originalMaterial.name);
            materialRefs.Add(clonedMaterial);
            materialColors.Add(originalMaterial.color);
            Debug.Log(originalMaterial.name);
        }

        r.sharedMaterials[n] = materialRefs[ materialNames.IndexOf(originalMaterial.name) ];

    }
}