Mac Unzip .zip and .cpgz

Just had a weird problem where unzipping a downloaded file using Finder resulted in a .cpgz file; clicking this resulted in another .zip file and thus starting a loop.

I worked around by opening a command terminal and invoking the command like 'unzip' on the file in question and the file uncompressed correctly.

unzip myzip.zip

Here for anyone else who discovers this odd issue!