A second passport sounds glamorous. And in point of fact, it is glamorous. There’s no debating the matter. Possessing a second passport gives its bearer bragging rights and the ability to feel a wee bit like a spy, especially when he or she is traveling with both passports in tow.
So you want to get a second passport and feel like an undercover agent? Not so fast. The US State Department allows Americans to obtain a second US passport under two circumstances only:  when a particular passport stamp will prevent entry into certain other countries the bearer intends or needs to visit, and  when a foreign visa application’s processing time interferes with upcoming international travel.
The first loophole addresses diplomatic barriers to travel. The chief example here is the Israeli passport stamp. Several countries refuse to admit travelers with an Israeli stamp (as well as Jordanian or Egyptian entrance or exit stamps from Israel‘s land border crossings with Jordan and Egypt) in their passports.
With an Israeli stamp in your passport, you may be refused entry to Algeria, Iran, Lebanon, Libya, Saudi Arabia, Sudan, Syria, and Yemen. Anecdotal evidence from friends and various online sources indicates that some countries are stricter than others, with Lebanon and Syria particularly unbendable. The bearer of a second passport can alternate between passports selectively, thus making sure that he or she will not be refused admission for a years-old Israeli passport stamp at, say, the Damascus airport.
The second circumstance addresses the problem of bureaucratic delays. People with upcoming travel scheduled while their passports are unavailable as a consequence of a foreign visa application (or another procedure involving a foreign government) can apply for and receive a second passport.
The second passport is only valid for two years. In addition to the required form and photographs, applications must include evidence of upcoming travel and a letter explaining the applicant’s specific need for the additional passport.