Sorry, I know I've seen questions similar to this and I tried searching, but I can't find it. Feel free to merge as necessary...

The basic question - can I have two separate award ticket itineraries reserved, which don't technically overlap, but which it's quite clear I won't do both? (I intend to cancel the one I don't use, of course, probably a few weeks in advance.)

Background - we'd like to take a transatlantic cruise this fall. We're indifferent between two cruises, which leave one day apart from different European cities, and we're waiting to see which is the better deal as the date gets closer. I've got award seats to one city already. Right now, there's good saver availability to the other city on the next day, and I have enough miles to book that, too.

Will it create a problem by having a reservation that has me leaving the USA a few hours after a different reservation has me arriving in Europe? They're not actually simultaneous, but there's only about 2 hours in real time between the two. (Landing in Europe at final destination at 11:00 pm local time on a Friday, and other reservation would leave the east coast about 7:00 pm local time on Friday.) If it matters, both will likely be on different Star Alliance partners over the water and in Europe.

Thanks!