Yes they do, if you check the following audio files, one from Spain and one from Columbia. Both have different accents:
http://mylanguages.org/spanish_audio.php
Well, not by just travelling, but people who has a long stay in other countries change their accent. Pronunciation of a particular sound is a very different matter. I think, some of them could start to imitate that sound, but it wouldn't be natural.
I don't do that, well i know some people do that, like a friend, when he travelled to Argentina, he tried to change his accent but i think he got anger or something, and began to speak in his accent, and then, all the peole laughed about him.. so hilarious.