Hello,
phpdocx includes TCPDF for some PDF workflows. The current version doesn't include an option to exclude the autoloading of TCPDF, so we recommend you to use the version of TCPDF included in phpdocx or remove the autoloading of TCPDF in the Autoloader.inc class if you need to use other version of TCPDF.
A future version of phpdocx will include options to avoid the autoloading of TCPDF and other modules included in the library.
Regards.