Contradictions

[potioncat]

No: HPFGUIDX 156612

 
> Snow:
> 
> After much consideration of many possibilities I find that I like the 
> time-turner as the answer to Dumbledore's longevity. I'm not crazy 
> over the time turning storyline but it would answer the question.

Potioncat:
It would seem, based on PoA, that when the person uses the TimeTurner, 
it affects everyone. That is, all Hermione's classmates experience her 
in the 9 AM class. Of course, that has 2 Hermiones in 2 different 
classes---good thing they don't have fire drills! 

So, I'm not sure it would work that DD somehow used a TT to "become" 
headmaster at 2 different times.That was what I was thinking. I suppose 
a more realistic explanation (I really don't think it's a flint) is 
that DD became Headmaster around 1955, resigned for a while, and 
returned in the 1970s. There's only Dippet's portrait because whomever 
served in the interim isn't dead.

However, I agree, he could be using a TT for other reasons.