$ ./compare-test.pl .
The following entries appear to be duplicates, and warrant closer 
examination:
        Checksum: d41d8cd98f00b204e9800998ecf8427e
                ./file-01.txt
                ./file-1.txt
                ./file01.txt
                ./file1.txt
        Checksum: 520bd68306a6bd9aa586a80ee692c750
                ./file-2.txt
                ./file2.txt
        Checksum: 024cde173d464feee746320b300b5c35
                ./file-04.txt
                ./file04.txt
        Checksum: 3ef60d5a2fa552f395e154bb5418893c
                ./file-5.txt
                ./file5.txt