The Trump campaign has returned donations exceeding the legal limit to brothers Cameron Winklevoss and Tyler Winklevoss, co-founders of US cryptocurrency exchange Gemini. Earlier, Gemini co-founders Cameron Winklevoss and Tyler Winklevoss tweeted that they had donated $1 million in Bitcoin (15.47 BTC) to the Trump campaign, exceeding the maximum amount of $844,600 per person legally accepted by the Trump Commission.