Over-exposed negatives print with midtones too light (if you use your darkroom skills to print darks and highlights correct). Likewise underexposed negatives print with the midtones too dark (if you use your darkroom skills to print the darks and highlights correct). As Thomas points out, variations in negative development don't have much to do with it.
If one carries through a peg point from scene to paper, say a mid-tone instead of a highlight or shadow, then the mid-tones will typically print essentially the same, not too light, not too dark. This assumes development remains constant and that the mid-tones remains somewhere on the straight line. In this case the highlight and shadow detail will change around the mid-tone peg (moving lighter or darker as they fall off the film curve) and the mid-tones will print normally.
Mark Barendt, Ignacio, CO
"We do not see things the way they are. We see things the way we are." Ana´s Nin