A different version of "Attack on D" from near the end of season 2 episode 12?


So I heard this song in _Attack on Titan_ towards the end of season 2 episode
12 and when I compared it to the soundtrack, I found out it was called "Attack
on D".

However, the song in the actual episode (episode 12) has a piano part in it
and the 'la la la' part only comes in towards the end of the song.

Is it a different song? If so, is it available in the OST?

