Do you mean instead of clicking the 'Copy Address >>' button?
If you find this to be an unnecessary step you could add a Lose Focus action event to each of the fields from the Billing Address that performs an Enter Value Into Field On Screen action to copy what you typed into the Shipping address fields.
You will still be able to enter a different Shipping Address if you wish but won't have to click any more buttons if it is the same. Just a word of caution that if you went with this option and entered in unique Billing and Shipping addresses then before exiting the screen decided to alter the Bill To it will overwrite your Ship To.
Let me know if you have any further questions.