Be aware everyone else in the world, though, is taking the same thing twice unless the game tells us not to, because that's how D&D is played.
To be super clear (and bring this back on topic), no-one using dndbeyond is taking the same infusion twice, because the system doesn't allow it. RAW or not, it's a precedent.
And to speak to the general case, I don't think I've ever played with anyone who thinks "taking the same thing twice" is supposed to be beneficial, except in cases where it's called out as being stackable.
The infusion feature is called out for Replicate Magic Item (and only Replicate Magic Item, currently) because it's a whole class of infusions, not just one. "Replicate Magic Item (*)" being duplicable doesn't necessarily mean "Replicate Magic Item (Alchemy Jug)" is.
No. You do not have to be told when you can't. You have to be told when you can. The absence of being told you can't does not necessarily mean you can.
Ok, look. I've cited actual sources to you. Unless you can cite a source back, I'm not going to continue this. The only source you did cite contradicts you: you're right and I'm wrong about unarmored defense; you're explicitly banned from getting it twice. According to you, this is a waste of ink - you're automatically banned from taking anything twice.
Be aware everyone else in the world, though, is taking the same thing twice unless the game tells us not to, because that's how D&D is played.
Unarmored Defense
If you already have the Unarmored Defense feature, you can't gain it again from another class.
This is exactly what is stated under multiclassing for Unarmored Defense. I shouldn't have even have had to state this much. Except for a couple things allowing additional use options like with channel divinity. Nothing actually says you can stack the same feature multiple times. channel Divinity doesn't even allow you to stack number of uses. Only let's you use channel divinity all of it's optional ways that your things give you access to as long as they aren't the same thing.
Nothing in the book gives you permission to take things twice. You can't point to a single spot that says that you can take things twice. You never had. You pointed to a single spot where it says you can't. The fact that it says you can't doesn't magically mean that you automatically can.
Even Spell Casting doesn't actually stack in any way except Spell Slots and it actually calls that out in specificity that nothing besides your number of spell slots and that your spell slots are a pool that both of your spell casting classes draw from together. Your number of spells known and you have access to are separate for the classes and don't stack. you even end up in a situation that you can have spell slots that you can't actually have spells to use without upcasting.
You blame me for not citing things but you actually cite nothing that actually supports your claim yourself. Only things that your trying to make an inference from. Then you try to tell me what everybody is going to be doing in D&D.
To be super clear (and bring this back on topic), no-one using dndbeyond is taking the same infusion twice, because the system doesn't allow it. RAW or not, it's a precedent.
And to speak to the general case, I don't think I've ever played with anyone who thinks "taking the same thing twice" is supposed to be beneficial, except in cases where it's called out as being stackable.
The infusion feature is called out for Replicate Magic Item (and only Replicate Magic Item, currently) because it's a whole class of infusions, not just one. "Replicate Magic Item (*)" being duplicable doesn't necessarily mean "Replicate Magic Item (Alchemy Jug)" is.
This is exactly what is stated under multiclassing for Unarmored Defense. I shouldn't have even have had to state this much. Except for a couple things allowing additional use options like with channel divinity. Nothing actually says you can stack the same feature multiple times. channel Divinity doesn't even allow you to stack number of uses. Only let's you use channel divinity all of it's optional ways that your things give you access to as long as they aren't the same thing.
Nothing in the book gives you permission to take things twice. You can't point to a single spot that says that you can take things twice. You never had. You pointed to a single spot where it says you can't. The fact that it says you can't doesn't magically mean that you automatically can.
Even Spell Casting doesn't actually stack in any way except Spell Slots and it actually calls that out in specificity that nothing besides your number of spell slots and that your spell slots are a pool that both of your spell casting classes draw from together. Your number of spells known and you have access to are separate for the classes and don't stack. you even end up in a situation that you can have spell slots that you can't actually have spells to use without upcasting.
You blame me for not citing things but you actually cite nothing that actually supports your claim yourself. Only things that your trying to make an inference from. Then you try to tell me what everybody is going to be doing in D&D.