Every heat source has it's own wattage. Thermostats have a maximum wattage they can handle, usually around 500w. It sounds like you're using the ZooMed ReptiTemp, which has two plugs and can handle 500watts.
As Starmom said, it's not a good idea to plug different heat sources into the same t-stat, tho it CAN be done as long as they are the same item (i.e. different sized Heat pads, but not a heat pad and a lamp) BUT the different items will heat differently because of wattage.

If you wanted to use UTHs (and by the way, the Ultratherm Heat Pad from ReptileBasics is as thin as flexwatt and works great for a very good price, try looking into that rather than those cobra mat things), and that heat rope, you could do with one stat... as long as you made sure that the combined wattage didn't exceed 500.
For example, most of my tanks and tubs use ZooMed UTHs for heat. A 10-20gal sized UTH is 8 watts. 10 of those pads would still only be 80 watts... much lower than 500 and so safe to plug into one stat. That long power strip of Ralph's probably only has strips of flexwatt plugged into it, with low wattage. So he can plug that huge power strip into one thermostat and it can safely run everything. It's in fact a great way to plug in more cords than the t-stat has outlets for.

I hope that ramble helped...