The answer is maybe. Is it owned or leased? If leased, then no. If owned, then maybe. Is your account a new one? Then no. If it's not a new account, has it been migrated to AT&T? Then no. If it's still a Directv account, then maybe. Bottom line, call and ask.
If they are from accounts that own their receivers (i.e. public viewing) then you can sell them on eBay as owned. Just tell the buyer up front that it is up to them to call Directv to determine whether they can activate them on their account if they're residential - show pictures of the back with the RID numbers. Commercial accounts can definitely use them.