As BIP-39 does not prohibit repeated phrases, mnemonics like abandon abandon abandon ... can exist, and if the implementation selects abandon as the phrase to drop, all instances of abandon will be dropped. I recommend, thus, dropping phrases by their indices.
As implemented here: https://github.com/hashgreen/hoogii-wallet/blob/99f5d7b67df296eb8f2137200fe7d57d1c32cf77/src/tabs/pages/mnemonic/createMnemonic.tsx#L29
As BIP-39 does not prohibit repeated phrases, mnemonics like
abandon abandon abandon ...
can exist, and if the implementation selectsabandon
as the phrase to drop, all instances ofabandon
will be dropped. I recommend, thus, dropping phrases by their indices.Below is a reference implementation