SP 2 is the latest full build for CR 2016....
Um, The message says you cannot have an older version installed, so would that not be correct?
You can't have CR 2011 when installing 2013 and the same for 2016, CR 2011 or 2013 must be uninstalled first.
The only time that message would also pop up is if you had CR 2016 SP 1 and tried to install a full build installer of SP 2.
There are incremental releases also so it applies updates without having to uninstall first.
And actually even and Incremental install still does a full uninstall and then installs the update, it doesn't remove all of the registry keys though.