When a friend offered Patricia Buendia a free place to stay in Rio de Janeiro during last summer’s World Cup, she wasted no time booking a spur-of-the-moment trip to Brazil to revel in World Cup frenzy. Buendia, a software engineer from Miami, had arranged for another friend to drive her to the airport last June so she could catch her flight to Rio via Buenos Aires. But when her pal noticed Buendia’s U.S. passport poking out of her bag, she asked whether Buendia had the necessary visa required for all U.S. citizens visiting Brazil.

“I thought, 'What? I didn’t know I needed a visa,'” said Buendia, who panicked at the prospect of an expensive trip going down the drain.

Lucky for her, Buendia wasn’t sidelined. She asked her friend to race her back home to pick up her German passport. Buendia, who was born in Peru to a Peruvian mother and a German father, is actually a citizen of both those countries. (She became a naturalized American citizen when she moved to the U.S. for work.) Because German citizens don’t need a visa for Brazil, Buendia could fly into the country on that passport without any problems. (Peruvian citizens don't need a visa for Brazil either, but she did not have an active Peruvian passport at the time.)

“I almost missed the World Cup,” she said, recalling how she made it to the airport with less than an hour to spare. “My German passport saved the trip.”

Buendia is not the only world traveler who has discovered the advantages of holding more than one country’s passport, which is no longer the sole province of fictional spies like Jason Bourne. While experts say it’s nearly impossible to estimate how many people carry dual or multiple citizenships, given an increasingly globalized world, the number is certainly growing.

And though not all countries allow dual citizenship, many do -- or simply look the other way. The United States, for example, does not formally recognize dual citizenship, but it does not officially require its citizens, naturalized or otherwise, to renounce other citizenships they may hold through birth, marriage or other legal means.

For globetrotters, claiming multiple nationalities can offer many perks, says Peter Gulas, owner of Allied Passport, a visa and passport agency in Washington, D.C. However, he cautions, such travelers should be aware of the pitfalls, as well.

Access To The World

“Having more than one passport can certainly save you money,” said Gulas. “Especially if you’re visiting the country of your origin, you can always go back on that passport and not have to pay for a visa.”

U.S. citizens typically pay around $160 to get a visa processed for the countries that require them. Other countries, like Argentina, don’t require U.S. citizens to have a visa but do charge them a “reciprocity fee” upon entering the country -- created to counter the fees the passport holder’s country charges for citizens of that nation. If you can enter a country on a passport that doesn’t require a visa or reciprocity fee, you could save hundreds of dollars.

Having a preferred passport can also save time, as Marty Jones, a technical writer from Madison, Wisconsin, discovered. Jones, who was born in the U.S. to an American father and a Dutch mother, applied for his Dutch passport when he was pursuing a master’s degree in Belgium in 2011. Not only did it scrap the need for him to get a student visa, it made getting around Europe during his stint there easy.

“I’d fly often to Germany, where my sister lived, or visit the U.K., France and the Netherlands. The immigration lines for EU residents were almost aways shorter,” he said. But because he doesn’t speak Dutch, it has sometimes created some confusion when immigration officials try to converse with him in what they assumed was his native language. “That was sort of shameful for me,” he said. “But I plan to learn.”

A second passport can also open doors the first might not. Rasha Elass, an independant journalist who is a dual Syrian and American citizen, said that her Syrian passport afforded her access to countries that were “off limits” or risky for U.S. citizens. (Full disclosure: Elass has freelanced for the International Business Times.)

“Technically, I could have gone to North Korea with a visa. I could have visited Iran easily, and I could have traveled to Cuba,” she said, though she never did go to the aforementioned countries. “And my American passport gave me a green light to go everywhere else in the world.”

She did, however, travel to Yemen on her Syrian passport in early 2010, one year before the events of the Arab Spring. “I felt a lot safer traveling there on my Syrian passport. On my American passport, I would have felt more like a target. People look at you differently,” she said.

Indeed, certain countries carry more tarnished reputations in parts of the world, and Americans can be in the line of fire by virtue of their nationality.

“U.S. passports come with a lot of benefits. But they carry a lot of baggage, too,” said Gulas of Allied Passport, who himself is a dual American and Czech citizen through his mother. He says he feels more comfortable brandishing his Czech passport abroad. “If someone is going to come into an airport with a machine gun, they’re likely going after the Americans. That’s probably just me being paranoid, but it is a consideration.”

Navigating The Pitfalls

Of course, traveling with multiple passports doesn’t come without its problems, either. If a U.S. citizen enters a country on another passport, she is also forfeiting the rights afforded to her on that passport.

“It’s not always the best idea to have two nationalities while you’re traveling,” said Gulas. “Let’s say you were a naturalized American from Egypt, and you went back to visit on your Egyptian passport. If somehing happens or there is unrest while you’re there, you can’t go to the U.S. embassy for help. They would ask you if you entered as an Egyptian.”

Whether the American embassy would decline to help a troubled traveler out of a jam in that situation is unclear, but it would certainly make the situation tougher. If you entered as a national of a certain country, you would be treated as a national of that country, and not as a foreigner. That’s important to know in countries that may subject you to their military service or taxes. While there are waivers available in some cases, an unknowing traveler could get caught up in a military draft or have to pay fees he or she didn’t expect.

Presenting a different passport from the one you booked your ticket on can also be a problem. When Buendia purchased her airline ticket to Brazil, she included her U.S. passport number on the booking. She’s lucky the airline did not create any delays or hold-up when she presented her German passport at check-in.

“Technically, they could have refused her boarding. Or delayed it while they sorted it out,” said Gulas.

That’s why it’s smart to carry both passports with you, even if you don’t plan to use one on a particular trip. Beth Carmody, a dual American-Canadian citizen, learned that the hard way. On a trip from Montreal to Bogota, Colombia, Carmody didn’t carry her U.S. passport with her. But her flight was routed through Miami, where she had to go through American customs and check back in for the next leg to South America.

“I thought having an American passport in Colombia would put me at risk, so I didn’t bring it,” she said. “But when I got to the customs desk in Miami, they knew I was American and asked me to present my passport. When I didn’t have it, they asked me if I was renouncing my U.S. citizenship!”

Carmody assured customs that she had no intention of doing so and was just unaware that that she needed to carry it with her. “They told me I was legally required to travel with it and let me off with a warning. They made me feel like I was lucky to get through,” she recalled.

Always traveling with both passports is one of the tips David DiGregorio, editor of travel blog StyleHiClub.com, recommends on one of the most popular posts on his site: A guide to traveling with two passports.

His guide comes with a disclaimer that should be well-heeded for anyone who travels with multiple passports: It is “overly simplified...be sure to do the research pursuant to your specific situation.”

Gulas agrees. Every situation is different, depending on which passports you hold and where you’re going. “So much depends on which country you’re talking about -- and even which official you’re dealing with at the airport,” he said. “They’re god, in so many situations.”