Jyn Erso Is the Best Rancor Raid Character! (5.8+ Million Damage)

Does anyone know how Jyn's leadership Zeta ability will work? What I'm wondering is what if a player will gain 2 buffs at once (like baze with taunt and retribution) will this player gain 2*5% protection or just once. And also when a player regains a buff he already has, will this add 5% protection or will it not count as gaining a buff?