Overprint Errors On India Stamps

Hi all! As I have mentioned before, I have a few approval/appraisal books from the 50's that I discovered in a box/tote. I was going through one last night that has stamps in it from India and its different states. I scan the pages of these books to keep a record of what I have. As I was scanning, I noticed that some of these overprints seem to have errors of some kind. Was this a common occurrence with these stamps? The pics I have attached are screen shots of the stamps. I have not removed them from their pages yet. I thank you in advance.

The inverted NABHA impression is part of the hooded squared circle cancel of Nabha Head Post Office of Nabha State Post.

The top overprint is forged.

Kochchi 1923 8P on 9P SG O20, Chamba 1905 3P SG O23, Chamba 1907 ½A SG 41 and Br. India 1900 3P SG C1 all have normal overprints.

Thank you for the input! I appreciate it.

The cancel on Kochchi 1923 8P on 9P SG O20 is Pai type 18/Trowbridge type 4 combined datestamp and obliterator (recorded used 1920–35) of Trishshivaperur Añchal Office (est. 1890) of Kochchi Añchal (Añchal means Post), Trishshur (10.5276°N 76.2144°E), now in Trishshur district of Keralam state.

The cancel (month is either Jan or Mar) on the Br. India 1900 3P SG C1 stamp is Virk type 50/Franks type F2/Hurt type 1/Padget type 51/Proud type D5 combined datestamp and obliterator of Indian FPO 7 of C.E.F., which was located in Beijing from Oct 23,1900 to Jul 14,1901.