Agong Stamp - Different Colour Shades

Pos Malaysia released a set of three stamps on 11 April 2012 to commemorate the installation of XIV Agong. The stamps came with denominations 60s, 80s and RM1. The background colour of the 80s stamp is in blue. Different colour shades have been recorded for the 80s stamps. The normal background colour for the 80s stamp is dark blue. However, less common light blue has been recorded. The below image shows the obvious two different colour shades of the 80s stamp. I believe that other shades (between the two shades as shown at below image) may also occur.

left: less common light blue background; right: normal dark blue background