DEs, anonymity and the HBP

[cat_kind]

No: HPFGUIDX 123078


catkind:  An extremely random thought. 

The Death Eaters are to some extent into anonymity:  they go about
wearing masks, even when they're going to a meeting with no outside
witnesses that are expected to live to tell the tale (the Graveyard in
GoF);  they don't know the names of very many other DEs (Karkaroff is
unable to name many the Ministry don't already know about; Spy!Snape
isn't able to get at many names either, presumably, or a lot more
could have been safely behind bars, and he would have known about
Pettigrew. 

Even in PoA, people still think Sirius Black had been Voldemort's
right hand wizard. This would suggest the identity of said wizard was
unknown, even to the spies and turncoats among us.

If such anonymity is really the case, the Graveyard naming of names
would be a major change of direction. Perhaps a punishment, or
forcible rebuilding of solidarity after the break? 
But, and I'm heading in the direction of farfetched here,  IF DEs were
anonymous amongst themselves, how did they address each other at
meetings?  I hypothesise, in the tradition of all good spy stories,
codenames.

So I come to the random thought:  could HBP be a Death Eater codename
for Voldemort's mysterious second?
Admittedly it would be a bit odd given LV's supposedly pure-blood
politics, but he's already known to be a bit two-faced about that, and
it could be a snide way of keeping the second in his place. It
wouldn't be so unreasonable to suppose that not just LV and his
nemesis but also his second-in-command are half-bloods. 

Minor supporting arguments: LV is the only character we've come across
thus far who's interested in aristocratic titles, and it would save
all the bother of suddenly discovering a royal family. And Lord
Voldemort is itself a sort of codename.  
catkind  (not particularly serious about this one)