That won't happen, the exchange will be on only one of the two branches and thus will only accept transactions on that branch. So double spends are not possible unless the exchanges switches branch at some future time.
There's nothing stopping an exchange from offering LTC and LTC X11. Once the fork happens, there will be two clients on separate block chains.
I guess when this fork happens, I'll have a handful of LTC X11, and I guess I'll dump them for BTC at whatever bargain price they're selling for, as I can't imagine how this could end well.
I guess when this fork happens, I'll have a handful of LTC X11, and I guess I'll dump them for BTC at whatever bargain price they're selling for, as I can't imagine how this could end well.