[thejeff]

If they were poisoned or decaying, etc they should have disappeared at the end of the battle, with the usual stream of hp numbers or years above them.
They weren't mercs, were they? If the commander dies, I believe the mercs vanish.

Were they listed in the battle report as dead? The right number at least. If so it could be the battle replay bug, which does not necessarily depend on OS or version differences.