AN ULTRA-RARE error on a 50p coin has skyrocketed its value - you might have one in your wallet

The 50p coin is listed for a whopping £29 on eBay and has already secured four bids.

A rare 50p coin with both the 1992 and 1993 dates on it has appeared on eBay - and it's already secured four bids.

The coin is listed for a whopping £29 on the auction site and is up for grabs until Thursday.

The rare error is found on the back of the coin, which was minted during Elizabeth II's reign and was issued between 1992 and 1993.

Its dual dates make it a "valuable addition to any coin collection", according to the description on eBay.

It reads, "The coin's uniqueness lies in its dual date feature, which makes it a sought-after item among coin collectors.

"This coin is perfect for anyone who is looking to expand their coin collection or for those who are interested in British decimal coinage."

Collectors will have until Thursday to bid for the rare 50p coin.

Be sure to check any loose coins in your wallet—you might be sitting on a small fortune.

It comes after Brits were urged to check their change for another rare 50p coin, selling for more than 300 times its face value.

When the Kew Gardens 250th anniversary coin was produced in 2009, only 210,000 copies were in circulation, making it a hot commodity among coin collectors.

Because of their scarcity, the coins frequently fetch high prices on sites like eBay, with one making £160 after sparking a minor bidding war on the online auction site last week.

The seller said the coin was "circulated" - meaning they could have found the coin in their back pocket, in their wallet, or down the back of their sofa.

The tail side of the coin displays the Chinese Pagoda in the Royal Botanic Gardens, as well as a portrait of the Queen.

It drew interest from 29 bidders eager to get their hands on one of the Royal Mint's rarest coins.

Kew's Garden 50p was created to commemorate the gardens' 250th anniversary in 2009.

Only 210,000 coins with this design were ever produced.

The average price for the Kew Gardens 50p is £156.25, however, one seller received more than £700 for one when they sold it on eBay.

How do I know what my coin is worth?

You can compare your rare coin on online auction sites, or The Royal Mint website.

But remember that if you intend on selling your coin, the price you get will depend on what someone is willing to pay for it on the day.

And beware of fake coins; do your research and seek a professional opinion if necessary.

It follows coin collectors' excitement at the rare King Charles 50p coin that could increase its worth by a whopping 54 times.

And a minor detail missing from your 20p coun could make it 300 times more valuable.

Top 10 most valuable 50p coins

According to the Royal Mint, these are the top 10 most valuable coins, when they were made and how many were minted: