Making a copy of an IF_Block is not the same as using an existing IF_Block. When you use an existing IF_Block in multiple zones, a change made to the IF_Block in one zone will show up in all instances of the IF_Block. However, when you make a copy of an IF_Block, you give the copy a new name and the copy can now evolve independently of the original IF_Block it was copied from.
Two methods are available for making a copy of an IF_Block; these methods differ depending on where you start: