It depends, what components you are planning to install. Technically, you can install different components on one system, but I am sure that you will face with many problems, too. For example when you install a dual stack system or pure java stack system, some of the ports can be allocated by the other systems. For example, SDM port may be allocated by a disp+work process. Consequently, some of the engines cannot be started, sucessfully. This is a minimal problem. One another scenario is you can technically install all SAP BusinessObjects components into the same machine, but because of FIM and BO Enterprise are using some of the same files, you are facing with troubles. You can create many scenarios like this.
Because of this reason, you shouldn't plan to install all components in a singlebox.