WPF DataGrid extended “copy and paste”

Breadth vs Depth; think in terms of a tree of references with your object as the root node.

Shallow:

The variables A and B refer to different areas of memory, when B is assigned to A the two variables refer to the same area of memory. Later modifications to the contents of either are instantly reflected in the contents of other, as they share contents.

Deep:

The variables A and B refer to different areas of memory, when B is assigned to A the values in the memory area which A points to are copied into the memory area to which B points. Later modifications to the contents of either remain unique to A or B; the contents are not shared.

Create a copy constructor:

class DummyBean {
  private String dummy;

  public DummyBean(DummyBean another) {
    this.dummy = another.dummy; // you can access  
  }
}

Every object has also a clone method which can be used to copy the object, but don't use it. It's way too easy to create a class and do improper clone method. If you are going to do that, read at least what Joshua Bloch has to say about it in Effective Java.