I interpret this question as "STOP iTunes from splitting albums" not "fix albums split by iTunes". It never used to do this. I don't know when it started. A few years ago and it's just ridiculous that users should have to go into myriad albums and change album artist or artist or anything. This happens to albums purchased through the iTunes store, which makes the bug even more infuriating. This is the reason people more for Apple computers, to avoid this fiddling/utility B.S.
I'm usually level-headed about things, as Apple's tech support is generally good, but the number of iTunes inexcusable bugs is growing and this particular problem has been going on for several years.
If I buy an album on iTunes Store, it should NEVER get split in this manner. I'm sorry, but it's sloppy software design behavior.
Please fix this ASAP. It's super frustrating and should be embarrassing for a billion-dollar company.