On the other hand, TKD and Shotokan karate, say, are strategically compatible, so anything you learned in one is going to be applicable to the other—but then, since the two are technically so close, it's hard to see much point in `studying' one of them for a brief period if you're already doing the other; both are hard linear striking arts predicated on the overal strategy that each move should either end the fight or set up a move to end the fight, sometimes abbreviated a little misleadingly as `one strike/one kill'. If they're both taught in terms of maximum street applicability, they will look very similar to each other. So it's hard to see what the advantage to studying Shotokan would be, as vs. finding a TKD dojang while you're over there and getting some extra TKD training in while you're there...
Bear in mind to that since it's just going to be for the length of the trip, you aren't likely to get far enough in whatever the art is to get anything really useful technically anyway.