Is one expiation sufficient if a vow is repeated?

If one makes a vow several times, is one expiation sufficient?
If it is due to a single act, one expiation for an oath is sufficient. For example: "I swear by Allah that I will not speak to so-and-so," and every time he sees him, he says this phrase many times; one expiation is sufficient.
However, if he repeats it by saying: "I swear by Allah that I will not speak to so-and-so," and "I will not speak to the second so-and-so," and "I will not speak to the third so-and-so," and "I will not travel," each one has its own ruling; the expiation for the oath.