How to clone prices from another product:
Go to a single-product
In the Prices section, click on Manage
From the left navigation, click on Clone Prices
Search for the product to clone prices from
Click on the Clone Prices From This Product button
A few things to note:
ALL active prices from the source product are cloned, so even if there is already a price with that same name/label, it will still be cloned, thereby resulting in a "duplicate" price by label
The default price of the 'cloned price` becomes the new default price for that product
Account-specific price(s) is also copied