duo was renamed to meet. the original meet was originally named hangouts meet, which was distinct from hangouts the consumer product, but not from hangouts the business product, which hangouts meet (later "meet" and now "meet original") was part of along with hangouts chat (different from "classic" hangouts which continued the discontinued google+ hangouts) which is now google chat (not gchat aka gtalk, which got merged into hangouts).

in 2019, google announced gsuite hangouts users would be migrated to google chat and google meet (that's meet original) and consumer hangouts would be discontinued. in 2020 for obvious reasons the original hangouts cancellation and the other hangouts cancellation were both cancelled. eventually google launched google chat (for consumers) and google meet, and finally discontinued the last consumer hangouts. at this point i think all users of all of google's hangoutses have been migrated to one of the google chats or meets, or back to the google voice app (for voice customers). but if you're still using meet original you're supposed to migrate to meet (originally duo).