Useful free plugin.
Gives you a clone button in order actions.
This does create and save an identical copy of the order but you can then edit it before emailing the order details to your customer.
I dont think this type of plugin has the potential to break your site.
I cant see why anyone would rate it less than 5 stars.
EDIT of review below after developer added functionality.
Updated review - Thanks this does everything I need it to do now. The developer was super quick to respond to my feedback and now it is does exactly what I need it to do. Giving 5 stars for functionality but also for VERY FAST developer response to feedback. Great work!!
Initial review - It clones orders exactly so only if the same purchaser/user etc. Does that well. But I do a number of orders that are all the same but for different purchasers and so I want to duplicate an order but change the purchaser/user and it does not have that functionality. Would be better if it cloned as a draft (or maybe to 'on hold' status) so that you can then change whatever details you want before you mark it as processing. So I have deactivated as not useful for me.
It works okay, but it aint possible to edit the order items etc. So this plugin is only usefull if you want exact the same order. Since i dont want to force clients to create a account most dont do this and it aint possible to copy the client data to a new order.