The executive producers of "Return to the Titanic . . . Live," Doug Llewelyn and John Joselyn, denied charges this week that the ship's safe opened by Telly Savalas during last week's nationally syndicated live broadcast was actually empty when first retrieved from the ocean floor. The two were responding to charges made to the Associated Press by Hubert Henrotte, president of Sygma photo agency, which participated in last summer's salvage operation. Llewelyn and Joselyn, who also produced Geraldo Riviera's unspectacular unveiling last year of Al Capone's vault, acknowledged that their special Titanic broadcast did not mark the first time that the ship's safe had been opened or its contents removed. They said the corroded safe fell open during its retrieval, and the gold coins and purse inside were taken out, preserved and then replaced in the safe shortly before the broadcast.