Okay, I see some big disadvantages to this approach.

First, the regex is very displeasing. A good way to remove duplicate letters would be: s/([a-z])\1/$1/ig) { Take advantage of capturing parens and back-references!

More seriously, however, is that your code will match on such text as "this too shall pass". How do you determine which duplicates you want to remove and which you don't? Any solution which removes the backspaces in one step and the duplicates in the second step is doomed to failure.

Here's a better approach:

#!perl -p
s/.\cH//g;
[download]

However, that won't work properly if there are multiple backspaces in a row.

A more generic and robust solution would be to use col. (Shameless plug. :)