It appears that importing duplicate column headers changes the order of the arrays.
Also, body corresponding to header is incorrect.

Example:

input:

output:

[
                'description'  => 'Description 1',
                'description1' => 'Detail 1',
                'details'      => 'Description 2',
                'details1'     => 'Details 2',
],

It should save the order of the headers.
I will create pull request!