Voigtlander 28mm and 35mm Metal Briteline Viewfinder

[selma-1]

I have one Voigtlander Black 28mm Brightline Metal Vewfinder that appears to have the front glass multicoated. It has a greenish tint when looking at the glass from the front .. My Voigtlander Black 35mm Metal Brightline Viewfinder does not have this greenish tint but appears to be coated. Any ideas why the difference??