Is it permissible to pay Zakat in advance for two years, when it was paid to marry someone whom Allah enriched before the end of the Zakat's due year?

It is permissible to advance Zakat if one possesses the nisab. If one gives the advanced Zakat to a poor person, and that poor person becomes wealthy before the completion of the year, then the Zakat is valid and one is not required to re-issue it.