Steps to reproduce:
- Click Edit on first order, i.e 000000001
- Click Edit on second order, i.e 000000002
- Click Add Products on first order edit screen
- Select any product and click Add Selected Product(s) to Order
You'll now see that the contents of 000000001 are all of the product(s) from 000000002 - as well as the product you selected.
I've also noticed some strange behavior when it comes to placing the orders after editing them whereby for instance the editing of 000000002 will result in it's new increment id being 000000001-1.
I think this bug may stem from the
adminhtml/session_quote object (
app/code/core/Mage/Adminhtml/Model/Session/Quote.php). Does this mean that Magento can only handle the editing of a single order per session? Surely it would differentiate between the session objects using the parent entity id or something along those lines?
Edit: The same behavior is experienced when placing two orders simultaneously, which leads me to believe it's definitely related to the inability to split the
adminhtml/session_quote objects on a per parent order entity id basis.