Please note this is an old forum thread. Information in this post may be out-to-date and/or erroneous.
Every phpdocx version includes new features and improvements. Previously unsupported features may have been added to newer releases, or past issues may have been corrected.
If you are using the trial package it's normal; otherwise, it may vary based on the content, timestamp and others (the size of documents with the same content may vary, but only a few KB).