GigaC

This plugin allows you to manage the WooCommerce coupons per users.

WooCommerce Coupon User Management

pimwick

PW WooCommerce Copy Coupon adds a Copy link to the default WooCommerce Coupon pages. This makes it possible to duplicate an existing coupon.
<blockquote>
Check out <a href="https://www.pimwick.com/pw-woocommerce-coupons-plus/" rel="nofollow ugc">PW WooCommerce Coupons Plus</a> for even more features:
<ul>
<li>Clip Coupons – Be like Amazon! Require the customer to “clip” the coupon to activate the sale price.</li>
<li>Coupon Bulk Editor – Quickly change multiple coupons.</li>
<li>No Coupons Allowed – Mark a product so that it will never be discounted by a coupon.</li>
<li>And more!</li>
</ul>
</blockquote>

PW WooCommerce Copy Coupon

Does what it says!

You saved me about 10 clicks and 1 minute each for 90 coupons I had to setup. That is worth a 5 star review.

Did what it says it does.
Works out of the box.

Once installed, on the list of all coupons, you'll see a third option when you hover a single coupon, besides Edit and Trash there will be a Copy action.
Once copied, the new coupon will be opened so you can immediately edit the title of the coupon.

I'm a developer and have inspected the code which is neatly organized and I didn't encounter any errors/issues while running the plugin.

Excellent and simple

Simply adds a Copy button to WooCommerce coupons to make it easier to create new coupons!

WooCommerce Coupon User Management vs PW WooCommerce Copy Coupon