Look at the dictionary entry.
mo•bile (mō′bəl for adj; mō′bēl′ for noun) [me mobyll < l mobilis, to move; 1480–90] 1 adj. easy to move; movable: several mobile homes were damaged by the strong winds. 2 n. a decoration made from pieces of metal, paper, etc., suspended on threads or wires and balanced to move in a slight breeze
in this case, why are two different pronunciations given for the word?
people pronounce the word two different ways depending on their regional dialect.
when two or more definitions are listed for an entry, each has its own pronunciation.
depending on its part of speech, the word has two distinctly different uses, which are pronounced differently.
adjective and noun forms of a word are always pronounced differently