You might want to notice exactly who the owners were of said collection -- that is, members of the greenfoot team, themselves. My guess is that they manually changed the property file of said collection to include multiple owners. The key word was "manually" -- since they are the ones with access to those files.
oh but I thought in some other collections too there were multiple. They have access to make their collection have two people! :0! but I notice not only in my collections, but in every collections, after the owners names, I notice a comma. that would have been done by them too, since they made two owners in a collection. Am I right?
I don't think so I found more...
*__* |
/___\ |
*argh*
I only found one(I guess SO!!)