(?<![,])"(?![,])

##</code><code>##

#!/usr/bin/env perl
my $test = '""crosby"","stills","nash","and sometimes "young""';
$test =~ s/(?<![,])"(?![,])/""/g;
print $test, "\n";
$test = '"som"ething","sil"ly","quo"ted"';
$test =~ s/(?<![,])"(?![,])/""/g;
print $test, "\n";
__END__
""""crosby""","stills","nash","and sometimes ""young""""
""som""ething","sil""ly","quo""ted""

##</code><code>##

$test =~ s/^"(.*)"$/$1/g;