I house Parakeets on one side & Canaries on the other.  However, 95% of the time the divider wall is left out of cage because they all like to hang out together. And in the matching single flight cage I house my 11 Zebra Finches, which they love.
These are the best cages I've ever bought, super easy & fast to clean. I just line the three removable trays w/newspapers. That saves $$ no more corn cob bedding to buy. It's really easy to move the cages around on their wheels. Vacuuming
around & under the cages is now a breeze. The only thing I dislike about the double cage is that you lose two sidewalls by having that removable divider.  You can't attach perch's, seed cups,or toys to it permanently.  They'd have to be removed everytime in order to pull it out.