Steps to Reproduce:
1. Create a Post-build Action of type Flexible publish

• Run? Always
• Action Post build task
• Script: echo "I am script A"
  So far so good. This works just fine. Now add a second one:
  2. Create a Post-build Action of type Flexible publish
• Run? Always
• Action Post build task
• Script: echo "I am script B"

Save the project and run.
Notice it runs Script A twice and Script B twice.
Also notice that if you click "configure" on this project, things have gone bonkers (that's a technical term):
There are 2 conditional steps, but they both have 2 script executions for the same condition.

It gets more complicated if you have different conditions to run these scripts: It merges them into one condition, making it pretty much useless.