* All the values are equally valid e.g. because a work has multiple authors

* All values are valid but one is preferred - usually the current value e.g. when we have population figures back over time or all the kings of Denmark. 

* One of the values is shown because it is widely used but is deprecated because it is wrong e.g. Beethoven born on 17 December 1770 (that his date of baptism so he must have been born a few days earlier).

The case described by Freidrich where we have two (or more values) which are both disputed (because they can't both be right) although one value is more widely supported then this is harder to represent semantically. I would go with adding a 'disputed by' qualifier to BOTH claims and marking the more widely accepted value as 'rank:preferred'

But that is just me

Joe