I wanted to throw this up because there hasn't been an actual thread for it's focused discussion. I was also just curious to read people's perspectives/(convictions even?) on where they stand and why.
Honestly even in the more restricted modern peasant cube I have no issue finding strong different cards that all do effectively the same thing.
Typically aggro decks need redundancy more than other decks so I need just a stack of 2/x for 1 and a bunch of good 2 drops but after that. Those 2 drops typically have different abilities, more power, +1/+1 counters or evasion but overall they are just better bears.
The midrange and control decks just want powerful effects of some kind regardless of its specificity. My mid range decks are actually very good at reusing effects through blink, bounce, recursion, reanimation and mana sinks and control decks have lots of card draw and make time to draw the specific cards they might need.
I think the only reason to break from singleton is if you are trying to do something specific (e.g Squadron Hawk) or trying to simulated a past limited environment with your cube.
I know that several people break singleton for lands/fixing. Particularly aggressive decks are perceived as having too poor options with most non-rare fixing lands entering the battlefield tapped, so several copies of City of Brass, Gemstone Mine or the like can be run.
A big draw of cube for me is the amount of unique interactions between cards, so functional reprints/multiple copies don't appeal to me. Gore-House Chainwalker and Thriving Grubs are close to mechanically identical most of the time, but the times when their fringe interactions come up (Skyship Plunderer with an immediate counter or Aether Chaser) makes the game play feel much fuller to me. Even if Looter Il-Kor is better than Merfolk Looter I wouldn't run 2 copies, since having a split makes for more different board states.
Doubling up on lands makes sense to me since having different lands don't add nuance to the board state in most cases.
I've only broken singleton for Volt Charge as I like the synergy it promotes even if isn't the most powerful burn spell. I do understand the argument of having different but similar cards that can maximise the different number of interactions in a cube. I find it weird though that sometimes people don't want to cube another copy of the same card, but are happy to cube a functional reprint with a different name. If you think the card with the new name is going to improve your environment, so will the another copy of the existing card, and you could have already just done that.
I haven't bitten the bullet, but I've considered cubing a second copy of some of the better green and blue aggro creatures (I'd consider Wingcrafter, Experiment One, Cloudfin Raptor and Kessig Prowler) to give those colours a bit more aggro support in the 1-drop slot.
Personally, I don't run functional copies nor strictly worses, even among different colours. It is a restriction I imposed myself to promote variety. I don't want two cards being exactly the same or the same but worse. I think that we have nowadays a high enough mean powerlevel in pauper to deal with that restriction without sacrificing enjoyment or power. To deal with the "aggro needs redundancy" issue, I appeal to colorless cards, that sometimes are slightly worse but are easier to cast.
It is a subjective decision though, so I don't consider it to be better or worse.
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My 490 Pauper Cube
Modern frame only- Common on paper only - no functional copies, no strictly-betters - no subtype-matters
Redundancy is achievable without breaking singleton. Like Purplemaralski noted, there are plenty of similar cards that help support archetypes while having interesting interactions. You can draft an aggressive RX deck two drafts in a row and see different interactions in each deck.
I do what merovingiann does, not running cards that can't ever be conceivably chosen over others, but have occasionally made exceptions things that I need (cough 1 drops). I don't do it for variance, but because I want as many decisions to be made by the players as possible. Seeing mind control vs control magic isn't a choice, and ending up with one while your opponent has the other isn't interesting.
Also, when I was running purely uncommons/commons I ran 3 copies of 5 color lands because I find dual lands to be somewhat distasteful. Everyone needs mana fixing because the game has a fundamental flaw with the mana system, and rolling even more dice in this area of the game is no bueno and worth breaking the "gimmick" of cube being singleton. Nowadays, I have gone on to include rare lands and the zendikar manlands but I also have other fixing at my disposal.
I'm also in the 'no functional reprints, no strictly-betters' camp. I do think this pushes my cube away from aggro and towards grindier decks, and I don't really support aggro strongly in all colors. That's a tradeoff I'm willing to live with, but it's a personal preference.
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"We plant the seeds of doubt to harvest the crop of wisdom."
Typically aggro decks need redundancy more than other decks so I need just a stack of 2/x for 1 and a bunch of good 2 drops but after that. Those 2 drops typically have different abilities, more power, +1/+1 counters or evasion but overall they are just better bears.
The midrange and control decks just want powerful effects of some kind regardless of its specificity. My mid range decks are actually very good at reusing effects through blink, bounce, recursion, reanimation and mana sinks and control decks have lots of card draw and make time to draw the specific cards they might need.
I think the only reason to break from singleton is if you are trying to do something specific (e.g Squadron Hawk) or trying to simulated a past limited environment with your cube.
Pioneer:UR Pheonix
Modern:U Mono U Tron
EDH
GB Glissa, the traitor: Army of Cans
UW Dragonlord Ojutai: Dragonlord NOjutai
UWGDerevi, Empyrial Tactician "you cannot fight the storm"
R Zirilan of the claw. The solution to every problem is dragons
UB Etrata, the Silencer Cloning assassination
Peasant cube: Cards I own
Cubetutor Peasant'ish-Funbox
Project: Khans of Tarkir Cube (cubetutor)
Doubling up on lands makes sense to me since having different lands don't add nuance to the board state in most cases.
I haven't bitten the bullet, but I've considered cubing a second copy of some of the better green and blue aggro creatures (I'd consider Wingcrafter, Experiment One, Cloudfin Raptor and Kessig Prowler) to give those colours a bit more aggro support in the 1-drop slot.
Cubetutor Peasant'ish-Funbox
Project: Khans of Tarkir Cube (cubetutor)
It is a subjective decision though, so I don't consider it to be better or worse.
My 490 Pauper Cube
Modern frame only- Common on paper only - no functional copies, no strictly-betters - no subtype-matters
MTGS Average Peasant Cube 2023 Edition
Follow me. I tweet.
Also, when I was running purely uncommons/commons I ran 3 copies of 5 color lands because I find dual lands to be somewhat distasteful. Everyone needs mana fixing because the game has a fundamental flaw with the mana system, and rolling even more dice in this area of the game is no bueno and worth breaking the "gimmick" of cube being singleton. Nowadays, I have gone on to include rare lands and the zendikar manlands but I also have other fixing at my disposal.
My CubeCobra (draft 20 card packs, 2 packs.)
430, Peasant, Very Unpowered
Why you should take your hybrids out of your gold section
Manamath Article
http://www.cubetutor.com/visualspoiler/7023
T2 powpercube Value https://cubecobra.com/cube/list/37t