The feud between OpenAI Sam Altman and Anthropic CEO Dario Amodei started long before the viral photo of them refusing to join hands in unity.Ludovic MARIN / AFP via Getty ImagesSam Altman and Dario Amodei's feud has fueled the rivalry between OpenAI and Anthropic.Now, the two leading AI companies are marching toward hotly anticipated IPOs.Here's a brief history of the AI labs' fierce rivalry.AI's biggest rivalry has only gotten more public this…