well there was a thread about this but after kevlarshark posted
People were having the very same discussion about multiple Hive tyrants with "Hive commander" FAQ = Do not stack
Or Multiple IG command squads with Astropaths. FAQ = Do not stack
I think the president has been set in many other codex.
The new core rule book in the special rule section states "Unless specifically stated, a model cannot gain the benefit of a special rule more than once."
Case closed.
the thread got closed, however, its not really that simple, as the rule states (as worded above) A MODEL, so what happens when you have two farseers? as thats two models......