For many of us, the prospect of planning and booking multiple trips at once might sound like the eighth circle of hell. Unfortunately, the eighth circle of hell probably has fewer entry requirements and travel restrictions right now than our favorite destinations. With the Delta variant surging around the world, and the fate of our travel plans directly tied to its spread, planning a vacation is more uncertain now than ever. That’s why “trip stacking” is on the rise — a new trend that serves as an insurance bet against vacations being canceled by forces beyond our control.

Public health concerns and ever-shifting entry restrictions have combined to create a deeply uncertain landscape for travelers. This is especially true when it comes to international travel. In early September, for example, the European Union removed the US from its “safe list” of countries, and thousands of Americans suddenly found their travel plans in flux. Many are responding to the uncertainty by pushing their trips to 2022, while some are waiting until the last minute to book. Others have fully embraced “trip stacking,” which involves booking two trips during the same timeframe with the hope that one will actually come to fruition.

One of the trips is usually a more aggressive trip — like traveling internationally or taking a cruise — while the second trip is often domestic and less likely to be canceled. If the international trip is canceled, the idea is to have a fallback trip you can take instead. And if neither trip is canceled due to COVID, the backup trip can simply be rescheduled at low or zero cost.

Joshua Bush, CEO of the Avenue Two Travel company, told CNBC that Mexico and the Caribbean often serve as popular backup destinations for travelers wary of putting all their eggs in the European basket.

“By and large,” he said, “cancellation policies have stayed really flexible, allowing the traveler to have that choice.”

The problem with trip stacking, however, is that it’s not exactly beneficial for the hotel, tour, and cruise companies who have to accommodate a flurry of last-minute cancellations. The exploitation of trip stacking could ultimately lead to hotels and other travel suppliers ending their flexible canceling policies, but that hasn’t happened quite yet. To avoid straining his relationships within the travel industry, Bush said his company only books simultaneous trips for a “small group of our very best clients.”

Trip stacking can also cause prices to skyrocket on hotel, airline, and cruise booking websites. Costs typically rise across these platforms as occupancy levels increase, and trip stacking creates something like a phantom rise in occupancy. That negatively impacts not just the platforms themselves, but other travelers looking to get a reasonable rate.

The bottom line is: if you have the means to book two trips at once, and the means to ultimately take both — go for it. Trip stacking’s impact on travel booking websites and price inflation is pretty minimal, and its chances of prompting a rollback of flexible cancellation policies is unlikely.