https://en.wikipedia.org/wiki/Convertibility_plan
The Real Plan in Brazil created a three month period with a combination of the old currency (Cruzeiros Novos) and a new virtual one (URV - Unidade Real de Valor) with an official daily exchange rate between them. This rate was selected to keep the URV at almost exactly 1 U.S. dollar but when both were replaced by a new actual currency (the Real), that was officially allowed to float relative to the dollar.
The real did initially get slightly valued relative to the dollar (an exchange rate of 1 R$ = 0.85 US$, for example) but floated slightly up and down until the end of 1998 when it suddenly jumped to 2 R$ = 1 US$ in order to block a huge wave of speculative money that was destroying economies around the world (having previously hit Russia, then the Asian Tigers).
From Wikipedia: "URVs were quoted in cruzeiros reais and its intrinsic value was pegged to three price indices and had a fixed parity of 1-to-1 to the daily U.S. dollar exchange rate."