  We show that uniqueness results of the kind those obtained for KdV and
Schr\"odinger equations ([7], [28]), are not valid for the dispersion
generalized-Benjamin-Ono equation in the weighted Sobolev spaces
  $$H^s(\R)\cap L^2(x^{2r}dx),$$ for appropriated $s$ and $r$.
  In particular, we obtain that the uniqueness result proved for the dispersion
generalized-Benjamin-Ono equation ([13]), is not true for all pairs of
solutions $u_1\neq 0$ and $u_2\neq 0$. To achieve these results we employ the
techniques present in our recent work [6]. We also improve some Theorems
established for the dispersion generalized-Benjamin-Ono equation and for the
Benjamin-Ono equation ([13], [12]).
