You're misunderstanding. They do occur in the same timeline and in the same universe as the mountains of evidence I've compiled have said otherwise. They're under no obligation to mention them as it's apparent what it is. No matter how much you try to declare that this is not true or this is true, Hasbro's word >>>>>>>>>> over any fan's wish for what happens in FIM's lore.
You mean the part in Luna eclipsed, it's clear cut an illusion she used to guise herself as nightmare moon even if she herself is not Nightmare Moon. The only thing that Luna revealed is how she can use illusions. Other than that, she showed nothing to indicate that Nightmare Moon and her are the same as she displayed no powers and such. Heck she had to borrow a fake fang set just to get the disguise right which further supports my opinion it was an illusion and not a perfect one as she can't change her teeth to NM's shape. The comics, Luna's and Nightmare Moon's contrast behavior, and Lauren Faust's word, which note, she would be part of the production of that episode I've mentioned, should prove my point. And in Do ponies dream of magic sheep, it was in her dream and nightmare she personally created just so she can personally self inflict herself.
So you're defending this as a desire for you to see Luna emerge most powerful just because she has some form that she must learn to control? Okay how about this:
According to the comics, as you see Celestia glow brightly, she has her own super mode too. Besides, why should Luna, whom according to the Journal of the Two sisters hated to learn magic that involved alot of work and reading compared to Celestia who busted her flank off trying to read all those scrolls and spells and even bantered with Starswirl to discuss about the spells and knowledge they shared should suddenly be stronger than her sister whom worked harder than Luna did to get as powerful as she did? There was a reason why it is canon Nightmare Moon is separate from Luna and it is because it is actually the only logical course for how Luna could beat Celestia as the lore has built Celestia up to be stronger than Luna is. The show itself has done nothing to suggest otherwise while the comics and other media sources have instead built Celestia up to be stronger than Luna.
Finally, if you're going to go by Luna's quote of how Celestia cannot enter into dreams, than I will prepare to state, Fiendship is Magic Nightmare Moon issue aptly explained that even in that realm, Celestia's mental defense is more than strong enough to defend against Nightmare Moon despite NM receiving heavy aid from the creatures on the Moon where just one is able to effect a whole city of ponies dreams (hell they may have taught her the ability to go into dreams I believe), a plan to tire her defenses out by forcing Celestia to go and defend the ponies from the many recurring nightmares the denizens of the moon were doing, and even when NM finally broke through Celestia's mind after a tiring effort on Celestia's part, Celestia still kicked her flank out.