One thing that I’ve learnt from my Hong Kong trip… apparently Hong Kong Dollar banknotes are issued by three different commercial banks, each with their own design, but with similar size and colour scheme for the same value note.
The three commercial banks are the Bank of China, the Hong Kong and Shanghai Bank, and the Standard Chartered Bank – all under the governance of the Hong Kong Monetary Authority (HKMA) which also issues banknotes itself.
Banknotes are issued solely by the central bank in most nations – some with the coins handled by another agency. Hong Kong’s system is presumably adapted from UK, with the Pound Sterling being issued by seven banks beside the Bank of England.