  Let $\mathcal{R}_e$ be a finite commutative chain ring with nilpotency index
$e \geq 2.$ In this paper, all repeated-root constacyclic codes of arbitrary
lengths over $\mathcal{R}_{2},$ their sizes and their dual codes are
determined. As an application, some isodual constacyclic codes over
$\mathcal{R}_{2}$ are also listed. Moreover, Hamming distances,
Rosenbloom-Tsfasman distances and Rosenbloom-Tsfasman weight distributions of
all repeated-root constacyclic codes over $\mathcal{R}_{2}$ and some
repeated-root constacyclic codes over $\mathcal{R}_{e}$ are determined.
