Problem

You have a handful of devices you want to connect to the board, and there aren't enough power and ground terminals to screw them all in. 

Solution

Numerous devices can share the same power and the same ground terminal on a green connector.  If you have only 2 devices, simply twist the stripped ends of the ground wires together and screw into the terminal.  Do the same with the V+. 

If you are going to be sharing the terminal with more than two devices, it can be a good idea to create a splitter.  You can solder (or even just twist) wires together to branch a single connection out into many.  This helps to improve the quality of the connection between the devices and the Make Controller.  It also is easier on the green connectors, which are not designed to handle too many wires jammed into a single terminal.   See below diagrams (the yellow wires are the signals).

 

            Sharing between 2 devices                      Using Splitters to share between 4 devices

Discussion

Screw terminals on the board that are labeled the same are indeed the same exact signal.  For example, all the terminals labeled GND are literally the same signal.  Same goes for V+, 5V, and 3.3V.  This is why it makes no difference, electronically, whether you split the wires as shown above, or connect wires to separate screw terminals.  Technically, the board could have a single pair, but that just wouldn't be very convenient. 

To split the wires:

• Strip 1/4" of insulation off the end of the wires you'd like to connect.
  
• Twist the exposed ends of the wires together.  For a stronger connection, solder them together.
• In either case, you'll want to either wrap the connection in electrical tape or heatshrink to make sure it doesn't come in contact with other pieces of metal and make a short.
  

Note: while this technique works fine for relatively low power projects, exercise caution when dealing with high voltage  projects.  It's not a good idea to split high voltage (over 48V) power to several devices.