A dedicated module is better, but if you're shy of that, another approach:

c:\@Work\Perl\monks>perl

use strict;
use warnings;

my @lines = (
  '50 0 "R0 G255 B0 A255" "Solid" 118 1 "R0 G0 B0 A255" "R0 G0 B0 A255
+" 0',
  '70 0 "R0 G255 B255 A255" "Solid" 118 1 "R12 \"G12\" B12 A255" "R12 
+G12 B12 A255" 0',
  );

my $rx_dq = qr{ " [^"\\]* (?: \\. [^"\\]*)* " }xms;

for my $line (@lines) {
    my @d_quoted = $line =~ m{ $rx_dq }xmsg;
    print "@d_quoted \n";
    }

^Z
"R0 G255 B0 A255" "Solid" "R0 G0 B0 A255" "R0 G0 B0 A255"
"R0 G255 B255 A255" "Solid" "R12 \"G12\" B12 A255" "R12 G12 B12 A255"
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