If you have an existing inventory item and you'd like to make another with similar settings and options, you can duplicate the existing item.
1. Navigate to Inventory in the main menu.
2. Find the inventory item you'd like to copy.
3. Click the gear to the right of that inventory item.
4. Select Duplicate Item.
5. Click OK on the confirmation dialogue.
This will create a duplicate item with all the same settings and options, but you'll probably need to make a few changes, such as renaming the inventory item so it's no longer listed as "copy."
Take a look at your Bookable Options. Any that were published in the original item are now unpublished. If they don't need any changes, simply click the gear icon beside each option and then select Publish Option.