Can you have multiple triggers for a given effect in a magic item?
Say there was a magus who wanted to have a device that protected him from fire (Ward Against Heat and Flames) and does so all the time (at least two uses/day, with environmental trigger: sunrise/sunset). Let's set aside the fact that this would cause warping because it's a constant effect. Say the magus received a death prophesy that he'd be burned to death and really, really wanted to protect himself from fire. But say he's also really paranoid and is concerned that someone might try and dispel the effect. If that were the case, he'd be unprotected from fire until sunrise or sunset and could be burned. So he wants to put in a second trigger, a command word, that will allow him to raise the protection again if it's ever dispelled. (Yes, I know he'd need more charges per day to make this tactic effective, and I realize that he doesn't really need the environmental trigger since he could just have lots of charges and raise it when he renews his Parma. Let's say he's really paranoid and is afraid of getting burned in his sleep before he can raise the spell again. He wants to make sure it's automatic. Work with me; this is just an example.)
So, can he have two triggers for the magic item, one an environmental trigger and the other a verbal trigger?
FYI: I'm not looking for clever ways to protect against fire damage. That's just an example I pulled out of thin air to make the point.
I would say you can. By RAW you have to add +3 levels for an environmental trigger, but having one regular "free choice" trigger and one environmental trigger should be covered by the normal +3 levels for an environmental trigger.
What if someone wants a load of effects, including multiple environmental, verbal and touch triggers? I'd probably want to add some room for manoeuvre, but you may want to insist on +3 levels per trigger past the first to stop players from layering too many triggers on.
Trivially, by RAW, I'm not sure. Does an environmental trigger replace a regular one or not? My impression from statements in HP is that it replaces the regular trigger. See the comments about when the effects start up in the necromancy chapter.
But could you pay for linked trigger multiple times, for example?
Of course if a troupe doesn't allow it, you can go another route: ReVi. Set up the effect you want with a regular trigger and several uses so you can fire it off if you're worried. Set up a ReVi spell to trigger it, that spell being triggered twice a day environmentally.
I was thinking about using a trigger word and then investing a CrIm enchantment that muttered that word twice per day, but that ReVi solution is much more elegant (and it doesn't let anyone know your trigger word because the item says it twice per day).