They could do the same by just sending some amount of south korean currency to every NK mailbox (or do it more throughly through records which I'm sure NK has k

They could do the same by just sending some amount of south korean currency to every NK mailbox (or do it more throughly through records which I'm sure NK has kept on almost every household), while maintaining two currencies to allow NK export firms to have a competitive advantage in cheaper currency, rather than suffocating them for a period of time after unification (as you can read in the link), slowing the economic recovery. "East German currency was exchanged for West German deutsche marks at a rate of 1 to 1, although the market rate was 4 to 1, according to the FSC. The overestimated currency conversion helped stabilize the livelihoods of workers from East Germany in the short term, but soon resulted in a sudden wage hike, which damaged the profitability of East German companies."