Agents enter dual agency when they represent both the seller and the buyer. Dual agency can happen even if the there are two agents involved -- a listing agent and a buyer's agent -- if both agents work for the same broker. That's because it is the real estate broker who creates agency.
The notion of Jewish control of the United States is utter nonsense. Jews are a capable people who have, through hard-work, gained a disproportionate role in some aspects of American life. But they in no way dominate the country.
The majority of the Jewish passengers had applied for US visas, and had planned to stay in Cuba only until they could enter the United States. But by the time the St. Louis sailed, there were signs that political conditions in Cuba might keep the passengers from landing there. The US State Department in Washington, the US consulate in Havana, some Jewish organizations, and refugee agencies were all aware of the situation.