You're assuming that \1 is magical inside of character classes -- I don't think it is. For example, the following works, and does what you want it to do:

I don't remember how to tell Perl to spit out how it parsed the regex, but that might be useful in proving my point, so I think I'll do that now. ;>

Update: Ayup. Here's what perl says about your regex:

Compiling REx `(")[^\1]*\1'
size 19 first at 3
   1: OPEN1(3)
   3:   EXACT <">(5)
   5: CLOSE1(7)
   7: STAR(17)
   8:   ANYOF[\0\2-\377](0)
  17: REF1(19)
  19: END(0)
[download]

Notice that it's taking the \1 to be chr(1), not a backref to the 1st value captured. By contrast, using negative look-ahead:

Compiling REx `(")((?!\1).)*\1'
size 24 first at 3
   1: OPEN1(3)
   3:   EXACT <">(5)
   5: CLOSE1(7)
   7: CURLYM[2] {0,32767}(22)
  11:   UNLESSM[-0](17)
  13:     REF1(15)
  15:     SUCCEED(0)
  16:     TAIL(17)
  17:   REG_ANY(20)
  20:   SUCCEED(0)
  21:   NOTHING(22)
  22: REF1(24)
  24: END(0)
[download]

Well, it's not quite so clear what it's doing anymore (at least to me) But it works, eh?

perl -pe '"I lo*`+$^X$\"$]!$/"=~m%(.*)%s;$_=$1;y^`+*^e v^#$&V"+@( NO CARRIER'