  We consider effects of $n-\bar n$ oscillations and resultant matter
instability due to dinucleons decays. We point out that existing upper bounds
on the rates for the dinucleon decays $nn \to 2\pi^0$, $nn \to \pi^+\pi^-$, and
$np \to \pi^+\pi^0$ imply upper bounds on the rates for dinucleon decays to
dileptons $nn \to e^+ e^-$, $nn \to \mu^+\mu^-$, $nn \to \nu_\ell
\bar\nu_\ell$, and $np \to \ell^+ \nu_\ell$, where $\ell=e, \ \mu, \ \tau$. We
present estimates for these upper bounds. Our bounds are substantially stronger
than corresponding limits from direct searches.
