This imperf stamps are also mentioned in Gandhi Handbook which has more imperf stamps than actual stamps.!!
I don't believe in Gandhi Handbook because it has incorrect information about stamps and philatelic material.
Even forgeries are also in Gandhi Handbook and there is no description or mention about that this is forgery such as 1948 Gandhi FDC from Indian Embassy Nepal or Gandhi SERVICE stamps on piece of paper and lot more.
According to me there are more chance of getting photocopy instead of IMPERF stamps.
It's very easy to print or make imperf stamps with latest printers or photo copy machine so be careful.
Most of the IMPERF stamps are nothing but forgery. Some times it's even bogus(never exist).
Some times it's STOLEN from Government Archives so be careful when dealing with some special philatelic material.
So be careful when you buy IMPERF stamps.
It's not a stamp !!