How are we supposed to answer that when only one pair of Kamui eyes has been displayed so far?
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It would obviously cause a paradox ,and either create a blackhole and transport them in an alternate universe, cancel each other out and render the attacks useless, or they are able to contact each other in their incorporal form and it will be a wasted battle of taijutsu
they;d have different dimensions. The same way FTG passes through a completely seperate dimension to teleport is the same way their kamui would get their own dimensions.
How are we supposed to answer that when only one pair of Kamui eyes has been displayed so far?
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Each one of these Uchihas has his both eyes ( so its not like Kakashi and Obito ) , if they fought will they share the same Kamui dimension ? or each Uchiha would have his proper Kamui dimension ?