From the Hall of Fame website.
Another practice of the media also upset Clemente. It did not involve his teammates, but rather had to do with his heritage and ethnicity. A number of writers and broadcasters insisted on calling Clemente “Bob” or “Bobby,” instead of his given name of Roberto. Even Clemente’s baseball cards listed him as “Bob Clemente,” a practice that persisted through the 1969 Topps set. Clemente did not like this practice, an effort at Americanizing him. He felt that it was disrespectful to his Puerto Rican and Latino heritage. When members of the media interviewed him and called him Bob or Bobby directly, he would correct them. “My name is Roberto Clemente,” he said repeatedly. In spite of his complaints, the practice of referring to Clemente as Bob, especially in print, would continue throughout the 1960s.
https://baseballhall.org/discover/ba...o-superstardom