I may be able to explain the presence of a third party hard drive, assuming the pricing situation in the U.S. was similar to that in Australia.

The original Mac Classic and Mac LC were both very expensive to buy with a factory fitted Apple hard disk. It was much cheaper to buy a floppy drive only Mac and install a third party hard drive. Most dealers gave customers the option of buying a Mac with a genuine Apple disk or a third party disk (in many cases, the same model Quantum disk that Apple used but without the Apple ROM).

Some less scrupulous dealers fitted a third party hard drive, charged full price and pocketed the difference for themselves. Sigh.