I did just the same...bought my perc's at the same time, same tank...and dont think you are being to picky when it comes to making them pick out the "exact " two that you want!
And just a lil note:...dont panic if they sleep up at the top of the tank on their sides right at the surface, under the filter return, a powerhead or even tucked between the heater and the glass...mine have a whole reef to play in and they return to the powerhead every night.
---Lori