I'll endorse ahmad's solution. I'd just point out that the magical quality of @ARGV can be handy for this kind of data munging and that chomp %hash chomps the hash's values.

Be well,
rir

#!/usr/bin/perl
use strict;
use warnings;

@ARGV = qw/ file1 file2/;

my %h;

while ( <> ) {
    /(\S+)\s+(\S+)/;
    $h{$1} = $h{$1} ? $h{$1}*$2 : $2;
}

print "$_ $h{$_}\n" for sort { $h{$a} <=> $h{$b} } keys %h;
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