Complex sentence: The LP was released in both stereo and mono formats and since-by 1968 -, most record compaines were discontinuing monophonic LP's-with the mono pressing is now an ultra rare collector's item.
Split into simpler sentences: The LP was released in both stereo and mono formats and by 1968, most record compaines were discontinuing monophonic LP's. Because of this fact, the mono pressing is now an ultra rare collector's item.