So the rules text of Twinning Staff refers to whenever you copy a spell "one or more times." But if you have multiple sources copying the same spell, like for instance if you cast a spell from the top of your library whilst controlling both Melek, Izzet Paragon and a tapped Kalamax, the Stormsire, would they each trigger Twinning Staff separately on the stack for a total of two additional copies, or would Twinning Staff only copy once since all of the copy triggers are targeting the same spell?
You'll get two additional copies.
Melek and Kalamax abilities won't resolve simultaneously: they'll resolve one at a time. Each time, Staff adds one copy.
would they each trigger Twinning Staff separately on the stack
To be precise, both Melek and Kalamax do trigger simultaneously. However, they will resolve separately, which is why Staff makes two additional copies.
See rules 603.3b & 608 for details.
Additionally, neither of them 'trigger' Twinning Staff. What actually happens is that Staff's ability will modify the effects of those two as they are happening.
See rule 614.1a for details.
or would Twinning Staff only copy once since all of the copy triggers are targeting the same spell?
Neither Melek nor Kalamax target anything. The word 'target' has very specific meaning, in Magic, and its misuse may lead to confusion.
115.10a Just because an object or player is being affected by a spell or ability doesn’t make that object or player a target of that spell or ability. Unless that object or player is identified by the word “target” in the text of that spell or ability, or the rule for that keyword ability, it’s not a target.
It seems as though the two abilities are separate. The first portion doesn't specify the type of spell so could it be used on a creature or artifact also.
I am trying to copy heart stone at least once with mirrorworks. From there I am hoping to use Xenic Poltergeist to turn the mirrorworks into creatures for a turn the text on mirrorworks does not seem to have a limit to how many times you can pay two to copy an artifact spell. With hearthstone and a copy with the now costless creature activated ability that costs 2 i should in theory be able to copy any artifact as many times as I want as the cost is now 0 for that ability. I am going to use that to copy from there I want to copy stone calendar to reduce the casting cost of spells to 0 as well as copy twinning staff and some other key artifacts. Then I should be able to have an unlimited options for how I can create an army, gain Life, Do damage etc. That could be limitless thus destroying the game fairly quickly. Is this on the right track?
It seems as though the two abilities are separate. The first portion doesn't specify the type of spell so could it be used on a creature or artifact also.
I am trying to copy heart stone at least once with mirrorworks. From there I am hoping to use Xenic Poltergeist to turn the mirrorworks into creatures for a turn the text on mirrorworks does not seem to have a limit to how many times you can pay two to copy an artifact spell. With hearthstone and a copy with the now costless creature activated ability that costs 2 i should in theory be able to copy any artifact as many times as I want as the cost is now 0 for that ability. I am going to use that to copy from there I want to copy stone calendar to reduce the casting cost of spells to 0 as well as copy twinning staff and some other key artifacts. Then I should be able to have an unlimited options for how I can create an army, gain Life, Do damage etc. That could be limitless thus destroying the game fairly quickly. Is this on the right track?
It seems you've misunderstood Mirrorworks's ability.
Mirrorworks's ability is not an activated ability (it lacks a colon, for example), but a triggered ability because it starts with "Whenever" (C.R. 602.1, 603.1), so Heartstone doesn't apply to that ability (just as it doesn't to any other ability starting with the form "Whenever ..., you may pay .... If you do..." [C.R. 603.1; see also C.R. 603.5, which applies to such an ability]). An activated ability's text starts with a cost followed by a colon (C.R. 602.1). Also, even if Mirrorworks had an activated ability with an activation cost (e.g., "2: Create a token..."), Heartstone would not "reduce the mana in that cost to less than one mana". See also this thread.
Mirrorworks's ability triggers "[w]henever another nontoken artifact enters the battlefield under your control", not when you cast an artifact spell.
When Mirrorworks's ability resolves, you may pay 2 only once for that ability (C.R. 608.2c).
Also, nothing in your scenario involves copying any spells (creating a token that's a copy of an artifact is not the same as copying an artifact spell [review C.R. 706.10]; compare Mirrorworks with Lithoform Engine), so Twinning Staff's first ability doesn't change anything in this scenario.
Melek and Kalamax abilities won't resolve simultaneously: they'll resolve one at a time. Each time, Staff adds one copy.
RULES OF MAGIC :
http://magic.wizards.com/en/game-info/gameplay/rules-and-formats/rules
To be precise, both Melek and Kalamax do trigger simultaneously. However, they will resolve separately, which is why Staff makes two additional copies.
See rules 603.3b & 608 for details.
Additionally, neither of them 'trigger' Twinning Staff. What actually happens is that Staff's ability will modify the effects of those two as they are happening.
See rule 614.1a for details.
Neither Melek nor Kalamax target anything. The word 'target' has very specific meaning, in Magic, and its misuse may lead to confusion.
RULES OF MAGIC :
http://magic.wizards.com/en/game-info/gameplay/rules-and-formats/rules
I am trying to copy heart stone at least once with mirrorworks. From there I am hoping to use Xenic Poltergeist to turn the mirrorworks into creatures for a turn the text on mirrorworks does not seem to have a limit to how many times you can pay two to copy an artifact spell. With hearthstone and a copy with the now costless creature activated ability that costs 2 i should in theory be able to copy any artifact as many times as I want as the cost is now 0 for that ability. I am going to use that to copy from there I want to copy stone calendar to reduce the casting cost of spells to 0 as well as copy twinning staff and some other key artifacts. Then I should be able to have an unlimited options for how I can create an army, gain Life, Do damage etc. That could be limitless thus destroying the game fairly quickly. Is this on the right track?
Also, nothing in your scenario involves copying any spells (creating a token that's a copy of an artifact is not the same as copying an artifact spell [review C.R. 706.10]; compare Mirrorworks with Lithoform Engine), so Twinning Staff's first ability doesn't change anything in this scenario.