Yes, "but" because the wireless one is so new, you installer may not have had one, or even known about them.
You might be able to call DirecTV and have them ship it to you [free] as you don't have the work order completed.
Now as to DECAs and receivers: any H/HR 24 receivers DON'T need/want to have a white DECA connected. Any other receiver needs to have one.
This is how all the receivers are networked, and then adding the CCK to this network is how the DECA "bridges" [not a modem] to your home network for internet.
I don't know if this will clarify or confuse, but the pics show what I have. The white "Connected Home Adapter" (first post) was on the back of the HD21. Now, I have a black DECA Broadband Adapter at the back of both HD24s. I have no clue why or what that means at this point lol.