#!/usr/bin/perl

# http://perlmonks.org/?node_id=1193751

use strict;
use warnings;
use Path::Tiny;

my %hash = map /^("\w+"),("\w+")/, path('file2.txt')->lines;
my $pattern = do { local $" = '|'; qr/@{[ keys %hash ]}/ };

path('file1.txt')->edit_lines( sub { s/^($pattern).\K"\w+"/$hash{$1}/ 
+} );
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