2 Cent Vertical Perforation - Normal Or Print Error?

Hello everyone, I bought a wonderful album here in Italy that contains a huge amount of US stamps. In the first image you can see only those of 2 cents that were contained in half page... I'll have to work one year just to classify them!
I have a doubt about two cases (below the photos) that have vertical perforation only on some sides. In both cases the perforated sides measure 11 x 10.5.
Is it normal or printing error?
Thanks in advance for anyone who wants to contribute. Stefano (steve :))

These stamps were issued in both panes of 100 and booklet panes of 6. The booklet pane is arranged in 3 rows of 2 stamps with straight edges on the left, the right & the bottom of the pane. Hence individual stamps will have 1 or 2 straight edges ... one on the left or right ... and if from the bottom row, an additional straight edge on the bottom. Panes were occasionally miscut ... the single stamp below the pair that has part of a stamp on its left is probably from a miscut pane.
Added: There are two types for this particular design, Scott 634 (type I) & 634A (type II). The more valuable of the two, 634A, was not issued in booklet format. There is also a more valuable color variety (634b, carmine lake in lieu of carmine) of type I.

Stefano ,
You can learn more about the varieties for this stamp here
http://stampsmarter.com/1847usa/192...ntifier.html
http://stampsmarter.com/1847usa/192...4vs634A.html
Don

Thanks you very much JLLebbert and 51studebaker, coffee paid when you pass through Italy :D