I'm not familiar with Japanese occupation notes.
However, I might be able to add a little information to the discussion.
Yes, the character at the lower right of the seal is chang (e•·).
The character at the lower left is zhang (ç« ). Zhang means "seal" or "stamp".
Unfortunately, the two characters at the top did not print well enough to identify.
However, since the last character (zhang) means "seal", the other three characters must be a person's name or refer to his office or position.
Chinese names usually have two or three characters. But during the war, it is not likely that a Chinese would be in a position to be stamping Japanese occupation notes.
Japanese names, on the other hand, usually have four characters. No name would end with the character zhang ("seal" or "stamp").
This means the three characters (excluding zhang) are probably not someone's name.
As already noted, the second to last character is chang (e•·). Names do not usually end in this character.
However, the same character (e•·) can also also be pronounced zhang and has the meaning of "chief" or "head".
I'm guessing that this is the meaning being used here. The stamp is thus the "seal" of the "head" of a government office or bank. The first two characters, which did not print clearly, would identify the organization.
Anyway, I realize that the above explanation does not answer your question as to what the seal actually means.
It's the best I can do, however, considering we can't read the first two characters.
Perhaps someone with more knowledge of these notes will be able to help you better.
Gary