Enabling startup and candidate in confd.conf

When I try and enable both the startup and the candidate, I get the following error during the “make …”

“Bad configuration: confd.conf:0: startup and candidate cannot both be enabled.”

Why is this not allowed? I must be missing some basic understanding.

If I don't, then then using 

netconf-console --copy-running-to-startup will fail.

Thanks in advance.

Please refer to the following posting for ConfD’s supported datastore combinations: