The problem is that [^\1] doesn't mean what you think it does.

perl -ne's/(.)([^\1]*)/print "$1-$2\n"/eg;'
A234
A-234

AA
A-A

A-\
A--\

A-1
A--1

A-A
A--A

A1
A-1
[download]

See, the 2nd paren will match whatever it wants to. I'm not sure WHAT [^\1] means; it might be "anything but chr(1)", but I'm not sure.
--
Mike