"Multicore Disease" and "Minicore Disease" are synonymous terms.

The disorder they describe is related to, but distinct from, central core disease.  In central core disease, the mitochondria-lacking cores run the whole length of the muscle fiber.  In minicore disease, there are multiple, smaller core-like structures.

Like CCD, malignant hyperthermia can be associated with minicore disease.  

Some people with minicore disease are developmentally delayed.   

Type 1 fiber predominance often occurs.

References:

Katirji, B., Kaminsky, H.J., Preston, D.C., Ruff, R.L., and Shapiro, B.E. (Eds.) (2002). Neuromuscular Disorders in Clinical Practice. Butterworth Heinemann, Boston. (ISBN:0750671696)  Pp. 1114-1127.

Prayson, R.A., and Goldblum, J.R. (Eds.) (2005). Neuropathology. Elsevier Churchill Livingstone, Philadelphia. (ISBN:0443066582)  Pp. 537-581.