NEW YORK, Sept 3 (Reuters) - A bitcoin company tied to President Donald Trump's two oldest sons more than doubled in value in its stock market debut on Wednesday, valuing the sons' stake at well over $1.5 billion as the first family grows their crypto business interests. Shares in American Bitcoin Corp , a bitcoin miner, soared as high as $14.52 in its first day of trade on the Nasdaq, before pulling back to be up 16.5% at $8.04 by the end of the day. The company is around 20% owned by Eric Trump and Donald Trump Jr, American Bitcoin...