A number of Twitter accounts masquerading as notable cryptocurrency developers and startups have been soliciting funds with promises of major gains.

With the rise in value and popularity of cryptos, such scam accounts have been on the rise – asking for small donations of various cryptocurrencies on the social media platform. In exchange, these scams promise, they will later send several times the amount donated back to the originating address.

Often this exchange will come under the guise of a giveaway: a “developer” will encourage fans to donate within a limited period to be able to participate, or they only send funds to the first 50 or 100 users responding.

What is notable (and disappointing) about these accounts, though, is that several of them appear to have been successful in scamming cryptocurrencies from users.

Data collected by CoinDesk indicates that these users have received a combined total in the thousands of dollars over the last several days.

For example, user @SatoshiLitev, copying the username of litecoin creator Charlie Lee (@SatoshiLite) offered to donate four litecoins to the first 60 people to donate a fraction of one to an address. According to Block Cypher, the address received a total of 11.5 litecoin (worth $1489.56 at press time). The coins were transferred to other addresses soon after.

Similarly, ethereum creator Vitalik Buterin (@VitalikButerin) has several copycats.

One, @VittaliBuuteri, offered to send two ether tokens to anyone who sent him 0.1 tokens. Etherscan data indicates that while people sent him ethereum, he did not send any back to those specific addresses. Another user, @vitalic_buterin, made a similar offer. Etherscan showed he had a balance of 2 ether from several donations as of Thursday night.

Individuals are not the only ones being copied. A copycat of Ripple, the company behind the XRP token, offered to donate 100,000 tokens to the community provided individuals first sent it 100 XRP. The account, @RippleOfficial, took pains to ensure it looked like the real Ripple account (@Ripple) by tweeting and retweeting the same posts as the company account.

And of course, some of the developers being copied are not happy about the trend.

Ripple chief executive Brad Garlinghouse commented that “impersonators [have] (frustratingly) become very relevant” after “@bgarlinghaus” tried to scam his followers.

The account has since been suspended by Twitter, but cached archives from Google show the user offered to donate 1 million XRP tokens in exchange for smaller donations on at least two occasions. It is unclear whether any XRP was sent to the user’s address.

Similarly, Vitalik Buterin commented on Wednesday that deleting scam accounts one at a time was ineffective, advocating for a system that would filter copycat accounts or a “better reputation system.”

His concern was that there were more than 800 possible permutations of his name by changing a single character. Changing two characters increased that number to nearly 350,000. As if to prove his point, the account Buterin was specifically referencing was suspended, but in his tweet responses people listed at least two more scam accounts.

It is unclear what efforts Twitter is making to remove these scam accounts on a larger scale, though at least two accounts have already been suspended.

The ethereum creator later joked about the situation, saying if anyone sends him 0.1 ether, he will respond with nothing as he is “too lazy.”

Twitter image via Shutterstock