China 1949 UPU stamp

[Dr Dave]

Thanks Roman.
I have the images you sent and I have attached them to this message
Please help me understand:
Are the images shown of a fake and of a real overprint? If so is the upper image the fake?
You mentioned there are two types of overprints for NW94... My lack of knowledge is in understanding what "NW94 char type b" means as noted in Yang catalogue. Is this refer to a special font/character type used at time of overprinting? Is there also a type a? if so, are they shown in the two images attached you sent me? If yes, then which is type b and which is type a (if there is a type a).
Hope this not to confusing for you because it is complicated for me to understand with my limited knowledge of China stamps.
Anyhow, any assistance you can provide is greatly appreciated.
David

[Roman]

HI David,

these are two genuine overprints (type a and type b).

This is how a fake overprint looks like (just one example of hundreds):

[Dr Dave]

Thank you kindly Roman
David