About Copying and Pasting in Assembly
With the Copy, Paste, and Paste Special commands you can easily duplicate and place components in an assembly. You can create instances dependent or independent of the source component. While the dependency of pasted features in Part Modeling refers to geometry, the one in Assembly refers to the placement of the pasted component.
When you paste a component the Component Placement tab opens. The placement references of the source component are maintained as a temporary interface. Drag the placement rubber bands to choose the assembly references or click the Placement tab and provide the appropriate assembly references. Temporary interfaces make it possible to add multiple occurrences of the same component. To keep the original placement references without using temporary interfaces, set the use_temp_interface_for_paste configuration option to no.
When you use the paste special options you can create a number of objects:
A new instance of a fully dependent copy of the component or of a dependent copy with different dimensions and annotation elements
A moved or rotated copy of the component
A new instance of the copied component with different placement references