Yeah, it's so strange that several songs got left off the official Above the Rim soundtrack, but could be found on the Regulate maxi-single or the companion Music from Above the Rim miniature soundtrack. Not just Pain and Loyal to the Game, but also Lord G's Mi Money Rite appeared on some versions as well depending on whether you got the Regulate maxi or the Music From in the US, Europe, or Asia.
If you're interested in buying some hard copies, some private sellers have them on Discogs.com.
https://www.discogs.com/master/115674-Warren-G-Nate-Dogg-Regulate-Music-From-Above-The-Rim
https://www.discogs.com/master/188384-Various-Music-From-Above-The-Rim
yeah and did they even have a reason for not just putting all these joints on the retail cd and just having the same tracks on all releases