Can a threaded fastener stretch so much it can be miss-read as a different pitch?

Can a threaded stud of mild steel, size 5/8"-11 over a threaded portion of 1.25" stretch so much over time that it reads 5/8"-13?

Unthreaded portion of the stud reads .625-630" in diameter, threaded area is in the .610-.605" range, there is visible thread blunting/wear, more progressive the closer you get to the end of the stud.

I know the M16 x 2.00 is sometimes miss-read as 5/8-13, but my M16 x 2.00 die does not chase over the stud, and my tap does not work through the stud’s accompanying nut.

I know the machine it comes from is old, and though I’ve never seen it, I’ve heard of proprietary threads, so before I go crazy looking for/trying to make a weird sized tool, I figured I’d ask.

So has anyone ever seen a thread stretched so far it reads a different pitch, yet visibly, it doesn’t look so deformed?