In fact, in the name of the language, the first l is normal, but the second l is retroflex ( मलयाळम )Even Vedic Sanskrit recognizes this sound. So, how come it is missing from modern Hindi? Well, probably because this sound isn’t used in the Delhi-Meerut dialect that became the standard dialect of Hindi. It is in the same category of retroflex sounds, which are relatively unique to Indic languages ( ण , ष , ढ , ड़ , ढ़ ). Except it isn’t part of modern Hindi, so speakers don’t use this sound.