No I would not. If I did plant two in an Earthbox, it would be a Regular. The regular has two wicking spots and the Jr has only one. There would be less conflicts over water and more space for nutes between them.@WildBill do you do two plants in an EBjr?
You could do it I guess, but you would have to make a pretty good size compost bank as your top dress mound. Two girls could eat up quite a bit of nutes. I guess the key is to not stunt one or get vastly different phenos. You wouldn't want one to overpower the other. I'd say photo clones would have the best chance of the best results that you could get with that set up.
It would be a good challenge with auto seeds. I would choose a stable girl with little variation.
Please tag me if you do. I'm gonna start updating my Earthbox thread with my theories and methods on them. Maybe I can make it into fixed go to thread with the info that I come about from doing and what others contribute.
Maybe something to leave behind when I'm dead and gone.