Very nice! I was stationed in Panama during the early 80's! The Balboa coins were an even exchange with US coins, and both would work in vending machines! I brought several Balboa's back with me!!!
The numismatic term of the word 'Unique' may be of interest to you. https://en.wikipedia.org/wiki/Glossary_of_numismatics#I
The reason they both worked was because they were made at the US Mint on the same planchets used for US coins.
https://libertycoinservice.com/wp-c...s-checklist-foreign-coins-by-us-mint-type.pdf https://en.numista.com/catalogue/pieces3034.html
Thank you. My dad traveled for his job so he had an assortment along with his USA change. So 20 plus year never touched.