Two teachers, a school staff member and a photographer have been practicing their curtsies for days. They've been chosen for the experience of a lifetime: A personal meeting with Queen Elizabeth and a garden party during Her Majesty's visit to Berlin.

But can they really be sure it's the Queen they'll be meeting? After all, they've never seen her live before. And the Queen isn't always the Queen.

Jeannette Charles was allegedly the first person in the world to successfully impersonate the British Monarch. A neighbor discovered her resemblance when she painted her portrait in 1971.

What followed was a 43-year career as royal entertainer, during which she met real celebrities like boxer Muhammad Ali and made appearances in the Hollywood comedies "The Naked Gun" (1988) and "Austin Powers" (2002). Charles retired in 2014 and passed away earlier this month.

Another Queen impersonator, Elizabeth Richard (pictured above), takes the commercialization of her doppelganger role even further and advertises herself on her website as "International Queen Elizabeth Lookalike."

She is booked for high-ranking corporate and private events around the world. She's curtsied for managers in Dubai and at lavish parties in Australia. Demand for her services rises, of course, when the royals are in the press for weddings, anniversaries or celebrations.

Realistically resembling the monarch can come with a hefty price tag, however. An authentic tiara costs 1,200 pounds (nearly $1,900), Richard told German broadcaster Deutschlandradio Kultur.

The 'real' impersonator

Ella Slack, on the other hand, doesn't rely on expensive accessories. Her Queen-like stature is enough: Could the two be twins who were separated at birth? For the past 20 years, Slack has been posing at Buckingham Palace, on The Mall, and at special events. Not only does the House of Windsor tolerate it, they give their blessing.

Once during preparations for a wreath-laying ceremony, the television crews had trouble adjusting their cameras. Slack, who worked for the BBC at the time, jumped in as a double - and quickly found herself with a new job. Since then she's served as a stand-in for the Queen in over 60 situations.

So far she's only met the real Queen once, when the monarch looked in on a rehearsal at Buckingham Palace.

Whether they're after money or fame, there are more Queen impersonators in England and the Commonwealth than can be counted. The London agency Susan Scott Lookalikes has six Queen doubles on their roster. In comparison, they only have five Winston Churchills - but 11 Elvis Presleys.

Working as a Queen impersonator means you have to be up for a gag. And since few average citizens have actually seen the real Queen up close, they're often easy to fool. Well known German choir director Gotthilf Fischer, for example, was set up in a television show in 1983. During the choir performance, the Queen drove up on stage in a black sedan, interrupted the music and handed to Fischer - visibly overwhelmed by that point - a bar of chocolate with a Union Jack on the wrapper.

The Queen online

Naturally, the Queen's twins make the most of social media to share their escapades. While the real Queen also has a Twitter account (@BritishMonarchy) with a substantial 1.1 million followers, she's been overtaken by Elizabeth Windsor's satirical account, @Queen_UK, which boasts nearly 1.3 million fans.

Here the Queen is shown the way many of her subjects would like to see her - as someone who can also smirk...

…and quote music legends…

…and even knows how to hold her alcohol.

But beware when you're online. There's so much Queen content on the net that it's often hard to distinguish parody from royal.

If the Queen offers the four chosen candidates a chocolate bar at the garden party this week, then they'll know for sure: She was fake.

This article was originally published in June 2015.

Click through the gallery below to explore places that will bring you closer to the "real" Queen Elizabeth.