indeed, for the rainbow there was officially a limit of one per customer. however, there are some people on telegram who were able to buy more than one and now offer them for excessive prices as mentioned above.
yes those people simply used multiple addresses or simply processed more than one order - I think the limit was only enforceable as to one per order. I don't think anything stopped them from placing a second, third etc order.
Maybe the post office knows this and they held back 20-30 of them knowingly so they could have their people eBay em for 10/20 x the price lol
otherwise what is their incentive to produce less stamps?