cobalt

Not sure why you guys think it was machined? I would have put it at hand filed. These are definitely hand stamped and sometimes internal mistakes happen. They might have mismarked it and needed to correct it at the factory. I doubt Porsche is going to scrap a case because someone didn't check to see if the 9 wasn't flipped around as a 6 or any number of different human errors. I can't tell you how many parts are on military aircraft that have a similar marking change and are completely traceable to heat and lot. I was put through hell for something similar to this in 1995 for parts on the President's helicopter. In the end the parts were used.

I would question why the existing stamp was cleaned with a fine file to lessen the impression depth more than anything. If they removed the number at the factory and marked it again, why wouldn't they leave it rough and same depth?

I guess we can only speculate but if it is important to you then pass.