Sorry, this is probably answered somewhere in the "playing multiple reactions" thread on BGG, but that's long and a little polemical, so I thought I'd ask here.
Sarah has one card left in her deck, and five in her hand. Let's say the deck card is a silver. She has secret chamber and market square in her hand. Her opponent plays a knight, trashing the silver and leaving Sarah with an empty deck. Can Sarah: reveal market square, discard it, gaining a gold, reveal secret chamber, necessarily drawing market square and gold, putting some combination of two cards on top of her deck, reveal market square, discard it, gain a second gold?)
(I think the answer is, surely yes; also, we can think of less contrived, but luckier, situations, where Sarah shuffles and happens to draw a market square, and then how can you know if it's "the same one" she already discarded or not?)