No, using another ID has a much higher barrier: more likely to get caught (it's the same ID, after all - tokens might (or should) be better anonymized so services don't build user profiles just using the age tokens), more likely to get punished (there's a real name attached to it), more likely to lead to a video verification request to compare ID picture with actual face.
Same thing as using the ID or photo of the same older brother : Nothing.
No, using another ID has a much higher barrier: more likely to get caught (it's the same ID, after all - tokens might (or should) be better anonymized so services don't build user profiles just using the age tokens), more likely to get punished (there's a real name attached to it), more likely to lead to a video verification request to compare ID picture with actual face.
Discord say they won't keep a copy of the ID, so getting caught for duplicate ID would contradict this narrative.
I don't see how this is worse than using a TAN list, or using someone's phone to circumvent 2FA.