I doubt much copper leaks from amalgams. Amalgams are probably less than 7% copper. While micrograms of mercury are toxic, the human body needs 2 or 3 mg a day of copper. So even if amalgams did release a number of milligrams total of copper over the years, this amount is not significant compared to what the body needs. Some people do have an excess of copper, but this is probably from well water with too much copper, perhaps cooking acidic foods in copper pots over a long period of time, or having a disease that causes too much copper accumulation.