Platy Grouping Questions...

[Aluyasha]

So I got a group of 5 Platies. Each have a different color (1 white mickey mouse, 1 normal mickey mouse, 1 sunburst, 1 neon, and 1 bumblebee).
My question is, they all keep swimming up and down the corners of the tank facing the glass, all in their own places.
I heard someone tell me once that their cory did that when it lived alone because it saw it's reflection and was trying to school with it.
I was wondering if Platies perfer to group with their own colors?
Should I have gotten all one color?
Just curious.