The tracks Within Attraction and Sand Dance are EXACTLY the same on the albums In Celebration of Life and Out of Silence.
Actually, no, they aren't. "Sand Dance" runs 5:15 on Out of Silence (1987), and depending on which release you have for the compilation album In Celebration of Life (1991), it runs 5:09, 5:10, or 5:16. "Within Attraction" runs 4:11 on Out of Silence, and depending on the release, 4:07 or 4:10 on In Celebration of Life. Those are just the playing times. I don't have multiple versions of these tracks ready to compare in my sound editor right now, but for all I know, one version could have peak levels at 68% and another version could have them jacked up to 98%.
Yes, of course, it's entirely possible that the exact same version of a track can appear on multiple albums. But, for example, if we know a loop started playing in 2001, and one of its tracks can be found on albums that were released in 1997, 2002, and 2009, we can be 100% certain where the track actually came from. There can be other clues, too. If it turns out four or five tracks can be found on the same album, it's unlikely that they were pulled from several different albums.
Again, we're trying very hard not to guess around here. We aren't just picking albums out of the blue when we tell you where a particular track is from. If we tell you it's from X, it's probably best not to mess around with Y or Z.