hexl-mode vs. repeated lines

[Dan Jacobson]

Even venerable od(1) can put *'s in so we don't have to waste screen
space with repeated lines,
0037540 0000 0000 0000 0000 0000 0000 0000 0000
*
0046300 2ff6 0251 094c 0d08 0050 0900 ba2f e87c
0046320 2f80 0251 094c 0d08 0050 0900 ba2f e87c

But does hexl-mode do that? At least its documentation doesn't give
such hope. 10000 identical lines vs. one little "*"!? Ought to be a
toggle or some narrow to region or something. At least document what
to do.

One also finds a binhex.el but what it is all about is sparsely
documented.