It can be hard to get enough copper in your diet unless you eat a lot of green veggies, and vitamins might block some of your ability to absorb it, so supplementing is a good idea.
I take copper for two reasons.
First, If you take a zinc supplement you should take copper because high zinc levels blocks copper uptake. And you should take copper at the different time than zinc because of that. (so a separate copper tablet at a different time of day than your multiple is a good idea).
Second, copper is essential for our immune system. If you want to ward off colds and flus, this is the way to do it with a regular supplement. I made a balm for cold sores of zinc/copper/tea tree oil that seems to make them go away in a day. (Copper and zinc kill viruses).
Standard copper supplement is 2mg. Too much copper can be toxic, so don't go crazy taking more, it won't help. Copper supplements are cheap. You can get a whole years worth for about $5. Swanson has some quality and good prices.http://www.amazon.com/gp/product/B00068TSEK