Well, not really, but there was a brief overlap between the finalization of his divorce of his first wife and the marriage license for his current wife being issued:
http://www.americablog.com/2008/07/mccain-was-still-married-to-his-wife.html
As the blogger concludes:
In all seriousness, putting the snark aside. Imagine if Barack Obama had two marriages at the same time. Imagine had Barack Obama lied about living with his first wife while having a mistress on the side. Imagine that all this happened while Obama had promised to speak out vocally about how gay people are a threat to marriage. We’d never hear the end of it from the Republicans and the media.
Imagine indeed!