Or, to put it more succinctly, was the two-RAM-chip motherboard seen in the Apple //e Platinum ever delivered in the previous-generation beige Apple //e Enhanced case?
My day-to-day machine is a near-NOS (it wasn't advertised that way, merely as "mint", but it certainly seems to. There's absolutely no trace of wear or use on the computer at all) //e Enhanced in the beige case, but contains the same motherboard (two soldered-in RAM chips) I normally see in //e Platinum computers. So I was just wondering if this was a machine built from parts, or if Apple ever actually delivered them that way.
The new motherboard was introduced with the Platinum redesign. There's a slight chance that as the last beige cases were rolling off the the assembly line, rev A(x2) boards became scarce and the newer boards pinched into production. It's unlikely though. It's far more likely your machines original main logic board became defective and was replaced by a service part.
Easy way to tell is to compare your date code on the MLB to the one on the pan.