New(ish) customer. Help me understand adding a receiver

I signed up for D* for the first time in late January 2012. HR34 and a H24. SWM, MRV, all the stuff you get when you start. Thought it would be enough but am now considering adding an additional H24 receiver for one of the bedrooms.

I know it's $99 from D* or Solid Signal. I also understand the 24 months for it.

But I'm already 3 months into my 24 month agreement and confused on what happens.

I emailed D* and got this:

I am excited to hear that you are considering adding another HD Receiver. DIRECTV significantly discounts the price of equipment and installation, so we ask you to agree to a programming commitment of 24 months effective when you accept and activate a new receiver. By adding another HD receiver, your programming agreement will be extended for another 24 months on top any programming agreement you may already be under.

That makes it sound like I've got my original 21 months remaining on my programming and two initial receivers, then D* will ADD another 24 months, totaling 45 more months just to get one more H24.

?

Or do I have one agreement in place for the programming/two receivers that has 21 months remaining, and then I'd have a totally separate 24 month commitment on the new H24, that would then need three months (full price of the completed agreement) of programming to satisfy that second 24 month commitment.

Or does the agreement just reset today and I have one agreement for 24 months from the new receiver activation, in which I have 21 months of credits remaining from my current agreement? Or do I somehow lose all my credits I was given as a new customer since I'm signing a 'new' agreement as an 'existing' customer?

Or what?

Kinda lost here...

PS I know I can do the 'buy an owned receiver than no agreement extension.' I'm just trying to understand how the 'add a new/leased receiver' works mid contract.