Yes, a few have surfaced, most notably “Mod Rock,” which reached the point of having an official catalog number and label art, but was mysteriously never put into production. Two copies came from Stan Cutler’s estate- one with full label art, and one without. More recently, a third copy appeared on eBay. “Mod Rock” was later given an official release, with audio mastered from the original studio tapes. Stan Cutler also passed on an early “Bluegrass” prototype (completely different from the official “Bluegrass Banjo” disc), as well as early versions of “Big Organ & Drums” (simply titled “Basic”) and  “Big Top Marching Band” (called “Circus”). Unique material from these prototypes can be heard on our Optical Organ Toolkit sample set.