You need to keep in mind that sometimes Rogers will get exhausted of cloning, and then you will need to take them out of the Cloning Room and place another couple inside. You will see a small green icon with an X above their heads when they are tired of cloning, so if that is the case, remove them because they will not do anything useful in there. Also you should create another Cloning Room as soon as you are able to, because that will speed up the cloning process and make it easier for you to get more Rogers.