I just read some hungarian and english articles regarding the hun leaders.
Unfortunatly there is many contradiction in them...
In many sources:
Mundzuk (Bendeguz), older brother of Ruga, father of Bleda and Attila, ruled at about 415-420
Rugila (Ruga), lived 365-434, ruled at about 425-434, and he united the huns by 432
Bleda (Buda), lived 390-445, ruled 434-445
Attila (406-453), ruled 434-453
But in another source:
In 434 Ruga was succeeded briefly by his brother Mundzuk, who was rumoured to have had killed him. For this Mundzuk was expelled and his sons Attila and Bleda became joint rulers of the united Hunnic tribes. Ruga served as an important forerunner to Attila
Because of these contradictions I think Mundzuk is out. I suppose some of the information is for Oktar, the third brother, but i cant really decide which ones...
And i think because Bleda was only a joint ruler with Attila (and of course Attila is already in) he won't be a good choice either.
So overally u are right, Ruga is indeed our best bet for a second LH!
EDIT: french sources about Mundzuk seems to be different too