Board Thread:Theories and Speculation/@comment-36512555-20200328202326/@comment-9782468-20200329212411

FlatZone wrote: https://naruto.fandom.com/wiki/Itachi_Uchiha#Mangeky.C5.8D_Sharingan He can use Tsukuyomi in both eyes, but Amaterasu in only his right eye. Did you actually just use your own edit as the source for this lol

In any case, it seems like @Snapper is right. Each Mangekyo gets one specific ability, so Itachi using it in his right eye is probably an error