My question
I'd like to know if the heroic and non-heroic version of the same trinket share the same internal cooldown for its procs? Does this behavior differ between trinkets or is it the same for all?
Context
I own the heroic and non-heroic version of the Iron Protector Talisman wich has a very strong proc (chance on hit to gain ~3k dodge-rating; i'm a druid tank).
If both trinkets share one internal cooldown, it would be better to just put on the heroic one and use another second trinket.
If both procs are independent, putting on both items should result in twice as much procs compared to a single one. Since i don't have much alternatives at the moment, this would be my setup of choice.
My research so far
I was able to find some information on wowhead about the internal cooldown that seems to be ~45 seconds.
I couldn't find information about shared or non-shared cooldowns.
Best Answer
I haven't raided seriously since cataclysm but at that time you could equip the RF/non-heroic/heroic version of a trinket and also the exact same trinket from a different raid level. The catch as I understood it was that they do in fact share an internal CD.
I tested this with the mastery trinket from DS(when it was current). The trinket itself was complete crap but I noticed that, while I was able to keep very high up time on the proc, I could never get it to stack.
This is hardly conclusive but I feel safe saying that the trinkets procs share the same internal CD just equiping 2 of the same makes it so you have a higher chance of keeping the proc up as close to as often as possible as you can possibly get.
This could have changed with MoP though, I haven't tried it since the expansion hit.