"Add Order" Option Prevents Parameter Selection for Multiple Orders

Current Situation
When adding two or more orders simultaneously using the "Add Order" option in a workflow with one or more workflow variables set to default values, the parameters of the second order cannot be selected if they have already been chosen for the first order.

Steps to reproduce

• Create a workflow with one or more than one workflow variable with a default value.
• In the Workflows tab. Click on "Add order" option
• Click on the "Add Order" option placed below the Modify variable option.
• Click on "Modify Variable" for Order#1 and select the workflow variable, and assign the value.
• Click on "Modify Variable" for Order#2 and select the workflow variable. Users could not select the variables for Order#2 which was already selected for Order#1.

Desired behaviour
Each order should allow independent parameter selection, ensuring that selection for one order does not restrict others.