Doesn't sound like one. It's not like Haka of Shielding where it's a single source of one-time DR but multiple sources of one time DR.
Edit: Thanks to someone else I was able to confirm in testing boards that this is correct behavior and has been that way in the game for well over a year at least. So not a bug.
If the way it works was changed and it is no bug right now, it means previously it was all the time a bug and nobody noticed it?!
Probably a Christopher ruling that got updated as has happened a few times. Making it not a bug but a Christopher dictated rule change. You can still submit it to Handelabra for review as I could be wrong on this.
Edit: Don't submit anything to Handelabra as its not a bug currently but the prior behavior described would have been.
Not a bug. In this case, the second didn't trigger because there wasn't damage dealt for it to trigger. (The first prevented it.)
Not a bug.
Heroes Unallied of Miss Informations deck says "Whenever a Hero target deals damage, redirect that damage to the Hero target with the highest HP. Then, destroy this card and play the top card of Miss Information's deck."
What if I play Coolant Blast with AZ and he deals 0 damage, should Heroes Unallied be triggered?
It shouldn't trigger as no damage is being dealt.
It's always you answering^^ Thumbs up
It triggered and I'll report it now.
Please note if you used Coolant Blast to hit Miss Information or another nemesis of AZ that would be dealing 1 damage because of the nemesis bonus and would cause that to trigger. Whomever it got redirected to though would not take any damage though.
The target was another hero and Heroes Unallied was discarded, after that Miss Information played a card :)
0 damage was dealt, no bonus or anything else happened.
For future reference, the easiest way to work out if damage was dealt - did anyone lose any hp? If no hp were lost, no damage was dealt :).
Lets have a look on the text of Heroes Unallied again:
The explanation of Powerhound implies that dealing damage means that the damage has to be > 0 at any point but it can be reduced to 0.
This contradicts the following explanation.
Regarding the explanation of Powerhound the requirement "dealing damage" was met and therefore the card triggered but finally nobody lost a single healthpoint.
Powerhound is the best. Amirite? Kudos to you!
I don't feel that Ameena's comment contradicts what I said. Heroes Unallied is dependent on dealing being dealt but if an attack by a hero target is zero on another target no damage was dealt and this doesn't trigger. This card probably should say "would be dealt damage" instead of the current wording.
The confusion here is coming from a lack of clarity.
The point is that it can be redirected to another target that doesn’t take as much damage (Scholar, Haka, etc.) And even though it still triggered the card because it WOULD have dealt damage (such as with a Nemesis bonus) it no longer does.
Maybe I found another bug, here is the situation:
http://imgur.com/a/6YkVt
Image 1: It's the end of turn of Miss Information, she uses her effect.
Image 2: You can see all the health of each hero and that he green grosser also should use his end of turn effect.
Image 3: It's the turn of the sentinels and if you have a look at the health of all heroes, you can see the green grosser didn't trigger at the end of Miss Informations turn.
Image 4: Double Click at the green grosser to display his effect (in the top right corner you can see that the sentinels should be the target)
Image 5: All effects in play
Image 6: All villain cards in play
Am I missing something or is it a bug?
I know that there is no Signature in play which is associated with a specific hero instead Sentinel Tactics is in play which is associated with all of the sentinels... Should I be able to choose a sentinel as target of green grosser if it's a bug?
Did Absolute Zero have Sub Zero Atmosphere in play?
I thought about that, but it's an ongoing and would make The Sentinels not the only possible target.
My answer is * shrug *, I need more information, do you have the save files? I aslways go grab mine if something funky happens so I can look over it in detail later.
No, as you can see the sentinels are listed as hero with the most ongoing cards in play.
They have 1 in play which means nobody else has an ongoing card in play 
I use an iPad, as far as I know no files are saved/available.