My first razor was the Merkur 33c, which is said to have the same head. Everytime I go back to it, I realize what a great razor it really is. The 38c being a 2 piece rather than a 3 piece, it would have to have different molds from the 33c. So there is a chance it could be slightly different. Throw in the tolerance factor, and wear to the molds, and your 38c head could be very different from my 33c, which I purchased 8 years ago. I believe Merkur remade some molds within that time frame, too.
It costs the company money to remake the molds, so I would assume that they wouldn't do that, unless they absolutely had to. Reasons like, bad mold, caused defective razor pieces, so in order to fix, had to re-make the mold.