  Lepton number violation is searched for at the LHC using same-sign leptons
plus jets. The standard lore is that the ratio of same-sign lepton to
opposite-sign lepton events, $R_{ll}$, is equal to $R_{ll}=1$ ($R_{ll}=0$) for
Majorana (Dirac) neutrinos. We argue that for "quasi-Dirac" neutrinos, $R_{ll}$
can have any value between 0 and 1, the precise value being controlled by the
mass splitting versus the width of the quasi-Dirac resonances. A measurement of
$R_{ll}\neq 0,1$ would then contain valuable information about the origin of
neutrino masses. We consider as an example the inverse seesaw mechanism in a
left-right symmetric scenario, which is phenomenologically particularly
interesting since all the heavy states in the high energy completion of the
model could be within experimental reach. A prediction of this scenario is a
correlation between the values of $R_{ll}$ and the ratio between the rates for
heavy neutrino decays into standard model gauge bosons, and into three body
final states $ljj$ mediated by off-shell $W_R$ exchange.
