Who Knows How Many Horcruxes Other Wizards Have Made?

[gelite67]

No: HPFGUIDX 148158

How did LV know that he had "gone farther than anybody living down the 
path that leads to immortality?"

How does he know that other wizards haven't created multiple horcruxes? 
I would think that would be something the other wizards wouldn't brag 
about.

Does his comment imply that other wizards who have since died ("anybody 
living")have created multiple horcruxes?

DD told Harry that he did not believe any other wizard had ever made 
plural horcruxes, but how does he know? 

Seems odd to me that the MOM would keep tabs on underage magic, which 
is generally harmless, but does not keep tabs on something like the use 
of Unforgiveable Curses of the creation of a horcrux.  

Angie