Pyapi service duplicated list objects causes reordering

[olofhagsand]

Pyapi service code can produce duplicates of objects, in the edit-config message sent to the controller.
In particular it can happen for objects that already exists on devices. That is, they are not "created" and thus do not have a creator tag.
Maybe it happens in other cases too.

See also clicon/clixon-controller#160 for workaround in controller