Usually it's lack of knowledge of the folks who build the library.
It's common for artists to generate a few bucks for themselves by re-recording old hits for a pre-established fee, and some labels specialize in these (Deluxe comes to mind, but there are several others.)
Additionally, when some artists changed labels, they re-recorded their prior hits from the old label, because the new label doesn't have rights to use the old label's masters.
Sometimes the record company itself uses an alternate take instead of the single version (Del shannon's Runaway was recorded in stereo just a few minutes after the mono version, but the phrasing is different.)
It takes knowledge and dedication to sort this stuff out--to know that Bybe Bye Love is only correct in the Cadence version but not on Warner Brothers, and Ray Stevens' material can be cross-licensed or remade, depending on the song and the source CD.
The market for remade hits flourishes, because, as Abe Lincoln aptly said, you can fool some of the people some of the time, and of course the fooled spend their money on this stuff, not knowing any better.
It's a daunting task for music fans, but even more so for PD's who have several formats to handle and not enough time to devote to getting things right.
More to the point, KMCQ's current format is a placeholder, so they're probably not spending much time on the finer points.
Good grief, their audio isn't even very clean, let alone what they put on it.
It's a shame, it could be done so wel, but you gotta go to the Internet for that these days. A few dedicated broadcasters there do it right--and play thousands of songs, not just a few hundred.
It may not be considered commercially viable for AM or FM, but it's a better listening experience.
