Section editing - overwriting wrong section

Scenario, there are two users and document like that:

== section 1 ==
sect content

== section 2 ==
sect content

== section 3 ==
sect content

1. UserA opens section 2 to edit
2. UserB opens whole document to edit ( no other way but with force editing )
3. UserB adds section 1.5 in the way it is:

== section 1 ==
sect content

== section 1.5 ==
sect content

== section 2 ==
sect content

== section 3 ==
sect content

4. UserB saves document.
5. UserA changes content of the section 2 and saves document.

The result is that userA saves overwrites section 'section 1.5' instead of 'section 2'.