Hi, the monogatari series has multiple CDs released for their OST.
Using nisemonogatari as an example.
Originally, all their OST is enclosed inside the anime's blu-ray volumes:
https://vgmdb.net/album/31153
https://vgmdb.net/album/31459
https://vgmdb.net/album/31677
https://vgmdb.net/album/31897
https://vgmdb.net/album/32102
However, they have released more standalone music collections:
https://vgmdb.net/album/68396
So the main difference is in the track listing, for example they all contain the same anime BGM, however the blu-ray versions have the OP song.
What I'm asking, is whether the soundtracks that have the same name are exactly the same in both CDs. Is it possible that the standalone music collection CD has better quality?
If I already have all the blu-ray bonus CD(i.e all the soundtracks the music collection can offer), is there any reason to purchase the music collection(eg. quality difference)? Other than for collecting.