At IBM one of my "other duties as assigned" was parts logistics and I spent a lot of time with parts. We would usually havew several different part numbers for exactly the same part. In some cases it might actually involve a better level of testing or a different stocking strategy for parts destined to different products but as often as not it was simply a price change. If they lowered or raised a part price it was easier to change the number of the new ones than to do the bookkeeping to adjust the price of all the parts in the parts stream.
One of the best kept secrets in the company was what "work" in an emergency. Usually a price change only was going to show up as a substitute part in the system but if it was a product related change it wouldn't "sub" even when the parts were identical.
