My open will capture both the STDERR and STDOUT messages.

No, it doesn't. 

$ cat main.pl 
#!/usr/bin/perl
use warnings;
use strict;
open (IN, '-|', 'perl PrintStdoutStdErr.pl') or die "$!";
while (<IN>) {
    chomp;
    print "\"$_\"\n";
}
$ perl main.pl 1>out 2>err
$ cat out
"this went to STDOUT"
$ cat err
this went to STDERR

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In reply to Re^4: Using IPC::Open3 instead of backtick operator by Anonymous Monk
in thread Using IPC::Open3 instead of backtick operator by rcrews

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