My cousin talks to herself,multiple personalities?

well the story is, my aunt jane was a drug addict and had my cousin lucy, she is 14 now, but her whole life before she was 3 she lived in her crib, never went outside still was fed formula from a bottle because my aunt was always passed out on drugs and would just give lucy a bottle every couple hours, she would just sit in her crib crying and talking to herself, she learned to talk by watching barney over and over, my aunt had it on repeat 24/7. so then my mom and dad came and took lucy when they saw how bad she was, and then my aunt came and lived with us trying to get clean and when lucy was 5 my aunt died from overdose, lucy was very traumatized, but while we had ber we taught her to eat and walk and go to the bathroom, and by the time she was about 7 she could have a conversation other then talking to herself and just parrot what ud say, and we thought we got her alot better and she quit talking to herself,we thought. she is 14 now, still developmentally about 9-10, but every time she goes to the bathroom i hear her talking to herself like she is 2 people. like she'll be like 'what are you doinb tonight? well im probably going to hang out with my cousin. oh what will you guys do?' etc. so i just want to know if maybe it multiple personalities or what? no body else knows she still does it really, like theyll just hear her talking and be like quit talking to yoursself lucy, but theyve never actually listened thru the door like i have, i know creepy.lol but i wanted to know what she was saying. but has anyone ever heard of something like this with emotionally abused children? is it multiple personalities or what?