IMPORT : Feature image issue

Dear All,

I am trying to import Featured Image in my posts using XML for the post & the image.
I found a guide to help me here : https://wordpress.stackexchange.com/questions/140467/how-to-add-featured-thumbnail-into-import-xml

However I still have issue. I created the attachment XML like said in the guide here it is:

<item>
    <title>701-1</title>
    <guid isPermaLink="false">https://africa-b2b.com/wp-content/uploads/2014/06/701-1.jpg</guid>
    <description></description>
    <content:encoded><![CDATA[]]></content:encoded>
    <excerpt:encoded><![CDATA[]]></excerpt:encoded>

    <wp:post_id>701-1</wp:post_id>

    <wp:post_date>2014-04-07 07:04:24</wp:post_date>
    <wp:post_date_gmt>2014-04-07 07:04:24</wp:post_date_gmt>
    <wp:comment_status>open</wp:comment_status>
    <wp:ping_status>open</wp:ping_status>
    <wp:post_name>701-1</wp:post_name>
    <wp:status>inherit</wp:status>

    <wp:menu_order>0</wp:menu_order>
    <wp:post_type>attachment</wp:post_type>
    <wp:post_password></wp:post_password>
    <wp:is_sticky>0</wp:is_sticky>
    <wp:attachment_url>https://africa-b2b.com/wp-content/uploads/2014/06/701-1.jpg</wp:attachment_url>
    <wp:postmeta>
    <wp:meta_key>_wp_attached_file</wp:meta_key>
    <wp:meta_value><![CDATA[https://africa-b2b.com/wp-content/uploads/2014/06/701-1.jpg]]></wp:meta_value>
    </wp:postmeta>
</item>

But what it soed is just creating another image in my media. OK, it is working but if i continue like that, everything will be duplicated… The only difference is the permalink.

How to solve this? Or find another way to import the featured image?

Thanks for your help