Perforation error in Singapore 2010 Year of Tiger 1st Local NVI

It is very rare to find major errors in modern Singapore stamp issues. This se-tenant sheet of 10 of the Singapore 2010 Year of Tiger 1st Local NVI stamp containing extra perforation on the right column just appeared on an on-line auction site. This error looks like an outcome of a shifted perforation process; this might mean the existence of another sheet of 10 of the same stamp, which is perforated only on the left column, and has no perforation on the right column!

Singapore 2010 Year of Tiger

For the Year of the Tiger, the Singapore Post issued on 8 January 2010, a set of 3 stamps and a collector's sheet. The stamps were for 1st local, 65 cents for Asian destination (Japan excluded), and $1.10 for Japan and the rest of the world.
The collector's sheet contains 2 stamps, with face values of $5.00 and $10.00, but it is sold at the post office for $16.80. These stamps are printed with transparent holograms, the hologram on the $5.00-stamp shows the morphing of an ox into a tiger - alluding to the transition from the Year of the Ox to the Year of the Tiger, while the hologram on the $10.00-stamp shows the morphing of a tiger into a rabbit, for the transition of the current Year of Tiger to the following Year of the Rabbit.
This is the third such collector's sheet issued by the Singapore Post, the first two issued in the last two years, starting with the Year of the Rat, and then the Year of the Ox. On the top left corner of the sheet are two ancient Chinese characters representing the word for "tiger".
The holograms on the stamps show up as shadows in my scan of the sheet.