No, you're not mistaken. When we reached Fishmen Island there was only one poneglyph
Yet now in this flashback we see there was originally two
So that means the
Road Poneglyph was shifted at one point, but we know Fishmen were trying to follow the promise for centuries, so doubtful it was them who did it.
We know as well though that Fishmen Island was Whitebeard's territory at one point, with him also having even back in the day an additional poneglyph that gave indication the position of the last one, so maybe it was him who did it