@MTastatnhgew  
She’s so fast she can appear to be in two places at once

@WinterCutieMark  
a Changeling.

@MTastatnhgew  
Obviously she has a stunt double for moments like this.

@Vortaxonus  
In the time between my comment and your reply, we have gained yet another counter-example of the theory. From the ending of Crusaders of the Lost Mark:  

@MTastatnhgew  
Yet discord is seen with own house in five, even though that intro is in season 4, and we never see him in flutter’s home save for one episode. Granted, theres the seen in crusade of the lost mark, but i do have a variation of this headcanon in that photo and rainbow are sisters, which Occasionally they swap places with for various reasons. This easily qualifies as a “collective identity” and has been done with gabby gums and the cmc. Don’t have any other supporting evidence, but it also deserves a fanfic (with feels, of course.)

It’s canon  

@WinterCutieMark  
The intro, as of season 4.

While there is really nothing that supports this silly theory, that in all honesty deserves a fanfic or two, there is also nothing that really debunks it. Did we ever see Photo Finish and Rainbow Dash in the same scene? Or episode for that matter?

So, any fics of this yet?

@Chaos Shepherd
 
Same here.

head canon accepted

Well, that’s stretching it but…OK.