> The recent incorporation into flyspell-large-region  of checking for 
> duplicated words has led to the following bug:
> 
> If a large region contains text of the form:
> 
> x$ $y
> 
> or of the form
> 
> x# #y
> 
> (where x and y may be any words and there may be multiple white spaces 
> between the $'s or #'s),
> then flyspell-large-region makes Emacs hanging (i.e. I have to press 
> Ctrl-g to make Emacs running again).
> 
> 
> I regard the following as a flyspell bug, too: If duplicated words are 
> separated by more than one white space, then they are not detected.

The attached patch tries to address these issues.  Please make sure that it
doesn't break anything else.