sub work_with_file {
    my ( $filename, $addon ) = @_;
    if ( open( FILE, "< $filename" ) ) {
        while (<FILE>) {

            $Datum      = $_ if m/Date: /;
            $Zeit       = $_ if m/Time: /;
            $errorFound = 1  if /Severity: Error/;

            $lines .= $_;

            #generate a new hash-hey
            if ( $Zeit && $Datum && $errorFound ) {
                $Zeit  =~ s/\D//g;
                $Datum =~ m/(\d+)\.(\d+)\.(\d+)/g;
                $dt = $3 . $2 . $1 . $Zeit . "_" . $addon;
                $Datum = $Zeit = "";
            }

            #put the error snippel in hash
            if ( /^\s*$/ or eof ) {

                $hash{$dt} = $lines if $errorFound;
                $errorFound = 0;
                $lines      = '';
            }
        }

        close(FILE);
    }
}

work_with_file($file1, ARGV[0]);
work_with_file($file2, ARGV[1]);