Sometimes it is easier to start with a copy of an existing item and modify it, instead of creating a new item from scratch. This is especially true if you have a lot of data in the optional item fields, that will be similar (you can also refer to the 'Preferences' section of this manual for information about setting default values for the fields in new items).
Highlight the item you want to clone and then click the 'Clone Item' button in the Item tab's button bar, or choose 'Clone' from the 'Item' menu.