If I understand your problem correctly, I recommend that you use a binding operator like so in case of a duplicate:

if (you-have-a-duplicate) {
   $data{$other_file} =~ s/^([^\|]*)\|/\1\/$other_file\|/;
   $data{$open_file} = "$open_file/$other_file|$status|$event_id|$msci
+_sec_code";
}
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This will add the filename to both the open file and the "other" file's entry.