There are very few, but off the top of my head:

1. Royal Guard / Coldheart / Seer / Septimus / w/e - for Spider 20, since you need at least two

2. Vogoth - potentially, since the healing stacks

3. Rotos - for arena

Beyond that, I mean, if I got another Big'Un / Nethril / Rae would I build it? Maybe, earlier, now, probably not.

I would use 3 of your armigers as chickens and get 1 to 60.  Don't think you need more than 2 for anything.  You basically have 5 useless champs at 40/50 instead of 1 useful champ lol.

You asked specifically about which you would build to use together not seperate builds for different teams, which is the wrong question lol.  Outside of a handful of niche cases (vogoth for me on Bommal), Tag arena is where I would build dupes.  

With Armiger, I think 1-2 is more than enough. Agree with Trips you don't need more than 2. 

For multiple champs in the same content...

Kramas is correct on RG/CH/Vogoth for sure. Definitely 2x Seer comps floating around in hard Doom Tower waves. 

Taurus in poison explosion comps comes to mind as a really good niche one. 

i have 2 royal guards built and 2 coldhearts

I would love a second brogni, or a second arbiter.

Oh if we're talking wishlist, I'll take two more copies of Lydia, please.

Thanks for the advice on Armiger, I'll consider getting rid of some. Seeing as they're only lv 50 though, they didn't take much to build, and I definitely would not take more than one to 60. Double Vogoth sounds interesting; that'd be for the arena I imagine? @Trips Wrong question? What should I be asking then? I wanted multiple builds to be excluded because you could argue any good champ that is somewhat versatile it's worth building multiple of for different areas of the game, and this not what I wanted to know.

There's a world of difference between a level 50 champ and a level 40 one. A level 40 champ can be useful early on for progression, and then later turned into food without any real lost resources. A level 50 champ had significant amounts of energy spent on it to reach 50, that you'll never get back.

The tl;dr here is - unless you have a good reason, just don't build more than one copy of a champ. There are very specific scenarios where that may not be true, but you shouldn't be building champs just for those scenarios, especially not early on.

I would keep 2 armiger, can use for fw21

https://plarium.com/forum/en/raid-shadow-legends/674_game-discussion/611550_how-do-two-vogoth-interact/

I have 2 CH and 2 Royal Guard.  I would definitly build another duchess if I had her for TT.

2 soulbond for my final rare secret room.  No masteries though! 😆 

I have mutliple Coldhearts built for Spider and FK. And two Roshcards to do my Block Damage CB team. :)

i

you lovely folks have any ideas what a guy can do with five deacons, maybe start a band?

Clear DT hard with a full Deacon team. 

Can we start with normal at least? 🙈