If that's the case, you'll need to make the hash storing the contents of the first file a hash of arrays (or, rather, a hash of arrayrefs) rather than a simple hash, so you can store each line that matches the id:

my %file1_row_for;
while (my $input = <THAT_FILE>){
    # only grab column 2
    my ( undef, $id ) = split /;/, $input;
    # add this line to the array of data for this key
    push @{ $file1_row_for{$id} } = $input;
}
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Then when you want to output it at the end of the line you can:

print join ';', @{ $file_row_for{$id} } if scalar @{ $file_row_for{$id
+} };
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Note that you'll just want to check for the length of the arrayref rather than definedness as in my original code.

perl -e 'split//,q{john hurl, pest caretaker}and(map{print @_[$_]}(joi
+n(q{},map{sprintf(qq{%010u},$_)}(2**2*307*4993,5*101*641*5261,7*59*79
+*36997,13*17*71*45131,3**2*67*89*167*181))=~/\d{2}/g));'
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