Al,
not CTO, genuine postal use for the 2 stamps. (Wanganui)
Not seen that auxilliary marking before.....strange
I cannot think why it is used, must be common usage to give rise to necessitate a rubber hand stamp.
This may answer your query
(Source: From the internet) Author : GlenCottage
Gives rise to whether they are CTO,

sharper minds may lend their opinions. I'll sit on the fence.
