currently obsessed with the idea that the dido we see in aeneid 1 and 4 isn't the real dido-- and not just because she's acting under the influence of venus and cupid. she's literally not the real dido, she's an eidolon, an imago.
because as vergil and his readers know, carthage was founded in 814 bce, and the trojan war ended in 1184 bce, 370 years too early for aeneas to actually run into dido. now there are a couple of ways you can deal with this: you can say that vergil moved the foundation of carthage 370 years earlier for the purposes of his story. or you can say that aeneas and his men travel to the 9th century when they go to carthage and then back to the 12th century when they leave for italy.
or you can say that actually nobody and nothing moves in time. aeneas goes to carthage in the 12th century, 370 years before it was founded by dido. he sees a mirage of a city ruled by a phantom queen. so when he goes to the underworld in book 6 and sees the shade of dido, she doesn't know him and turns aside because that's the real dido who lived and founded carthage in the 9th century and killed herself to avoid being forced to marry iarbas and never met aeneas. that's how the underworld works, it's populated by people who haven't been born yet by aeneas' time but are still there already dead. dido isn't like a ghost like anchises, she's a ghost like marcellus.