Also wanted mention that part of my career having been in electronics some which was both Final test and Military QA for Intel an unknown fact to most is that electrical components are tested to different criteria. During these tests there a different classifications assigned depending on a a components response to these tests.
They are sorted into categories such as a Bin1, Bin 2, 3, 4 or 5. bin 5's are rejects.
Bin 1's are considered a premium part and price d accordingly. Bin 2's a bit less, 3's less yet, 4's are the bottom of the barrel and are sold to places like Fry's electronics or other businesses more concerned with cost than performance or reliability.
Some companies will specify their own test criteria such as IBM, Apple, etc. as well as the Military. And OF course are much more expensive than Commercial grade Bin1's.
So when one looks at any electrical device (and likely other things as well) what appears to be physically identical MAY BE, because it is. It was made at the same time, on the same line, by the same workers, equipment etc. But performance and reliability wise tested poorly so it became a Pro comp part instead of an MSD, or other premium replacement item.
The problem is, only those selling and buying the part know what its category or quality is.
These same manufacturing principles apply to just about everything that is mass produced from drill bits to clothing
Thoughts to PONDER