What if each pink pony we see in the background is Pinkie pie clone who adopted a new personality.

Raving Pie

Private Pie

I accept this head-cannon.

5525059 May this headcanon live forever.

5525059

Different cutie mark, coat and eyes colors. (Her canon name is Pacific Glow.) The second one has been confirmed to just be a simple gag by the writers.

Now it is only a matter of time and motiiivation until somepony writes a series following the Pinkie-clones that appear.
Raving Pie is a single mother who became preganant after a wild night at a crazy rave that was stopped by the police. She followed one of the other party-goers and high on adrenaline that only the original Pinkie can handle and continue to act relatively normal, has a night of passion with hiim.
Private Pie is the original Pinkie Pie who hasn't given up on figuring out who the original one is on something more reliable than bad luck and attention span, like Twilight did. She is using the skills that she picked up on in "MMMystery on the Friendship Express" watching Twilight investigate, and refined those skills, all to figure out who the original one is and if she is lost in the Mirror Pool.

5525059 i like it. heck, for all we know, the one from the rav and the one from the dinner could be the same one and she was just making sure pinkie hadn't connected the dots