OpenCart has a replica : OpenCart Extra ???

Something has bothering me.    I found this site http://www.opencart-extras.com/ that claims developing OpenCart Extra based on OpenCart. Which one is officially right? Any comment about it?

opencart-extras is an offshoot maintained by Bruce and myself. We offer our release based on the 0.7.7 core with many bug fixes and enhancements. This is just to maintain an existing tree of the o.7.7 framework for people unable to upgrade from 0.7.7 to the later version(s). We still do support and use the OpenCart system, we just have our own code base that we use in preference for our clients and users.

-Dave

There is only 1 official OpenCart, and that is right here.