Duplicate Character in Translation Table

I got this message when decompressing a filename/img/gz (496MB) compressed disc image using SparkFS, where filename is a disc image containing a Ubuntu ‘distro’. The decompressed file, filename/img, is 1935MB in size. What does it mean? Does it matter?

What is the command for checking an md5sum checksum? I used to know it, but can’t find it anywhere. I wanted to check the original compressed file.

I have now decompressed filename/img/gz on my EeePC running Xandros, a version of Linux. No error was reported this time.

To answer my second question, I was using the correct command, but didn’t have the md5sum module loaded. It’s calculated the checksum, but I can’t see any md5sum published on the website from which I downloaded the disc image. Reminds me of earlier times on this ROOL website. :-(