  Spin chains have been proposed as a reliable and convenient way of
transferring information and entanglement in a quantum computational context.
Nonetheless, it has to be expected that any physical implementation of these
systems will be subject to several perturbative factors which could potentially
diminish the transfer quality. In this paper, we investigate a number of
possible fabrication defects in the spin chains themselves as well as the
effect of non-synchronous or imperfect input operations, with a focus on the
case of multiple excitation/qubit transfer. We consider both entangled and
unentangled states, and in particular the transfer of an entangled pair of
adjacent spins at one end of a chain under the mirroring rule and also the
creation of entanglement resulting from injection at both end spins.
