Copying is the fastest way to add an item similar to an existing one (same type, vendor and accounts, with a different name or price).
From Inventory → Inventory Management, find the item, click ☰ in the Action column and choose the Copy icon.
A small window asks for the new SKU. Type it and click OK.
The new item card opens with most of the original item's data. Change the name, barcode and price as needed, then click Save.