Maybe. This all depends on the type of equipment the installer installed. For example, if you have 2 dual tuners and the installer installed a DPP Twin LNB, you cannot add any more receivers without changing LNB type and adding a switch (DPP Twin only supports 2 receivers). If it is a 1000.2 or 1000.4 Dish, then you probably have room for one more receiver (single tuner or dual tuner). If you have a very non-standard install and the installer had to use a DPP44 switch, you can install 2 more receivers (single or dual tuner).
This also depends on your level of wiring diagram competence, and ability to run new cables if necessary. If you are at least a novice, and can follow directions fairly well, the people here can probably get you through it. If you don't think you can handle it, or if you try and fail, you can always pay dish to send a tech out to get it working.
One thing I will tell is BEWARE of buying new or used receivers on Ebay. Some people don't realize when selling their old receivers that dish may actually own them. Before completing any transaction on Ebay, get the R00 number from the seller, then call dish and ask them if the receiver can be transfered. If they say no, it means either the seller does not own it, or the seller owes dish money. They will not (or shouldn't) tell you why, but if they no, don't buy it!
As far as what equipment you have, here's how to tell. I'll post some screen shots to try to help, but since you didn't say what receviers you have they may not match exactly what you will see, but should be close enough for comparison.
Press "Menu" Then "6" then "1" then "1" again. You should see a screen similar to this:
You need to highlight the "check switch" button and press "select" on the remote.
You should now see a screen like this:
What we need to know is everything in the area highlighted below:
Just reply with the fields shown in that area so we know what equipment you're dealing with.
