Thanks for your reply.
Once I shutdown both engines, I cannot see if fire has gone or not anyway, and it only lead to evacuation procedure regardless of its necessity.
Another idea is that just wait for some seconds and see what happens after agent 2 discharge with another engine running. I think that's the only way to avoid unnecessary evacuation.
ECAM action just says shutdown remaining engine and it could cause that sometimes crew shuts the engine down instinctively because of such an urgent situation.