Lao is said to now be a language with phonetic spelling since the reform/standardization of the 1970s.
During this process some consonants were made obsolete (they're still not in Unicode) because they were only used for etymological spelling and more common letters represented the same sounds.
Yet it seems Lao retained two vowel letters that have the same sound: "ໄ" and "ໃ" both represent the sound
• Do we know why a duplicate vowel was retained while duplicate consonants were discarded? • Or are they distinguished phonetically somehow after all, possibly only in some dialects? • Or are they one remaining vestige still used for etymological spelling of Pali and Sanskrit words? • Could it be due to a merger ancient or modern?
In fact there's even a third way to spell
/ai/: "-ັຍ" and there seem to be other vowel sounds with multiple spellings as well.