Context: products from demo data

Behavior: When I refresh the page, the products images are not requested.

Context: product created from the interface, image from admin computer

Behavior: When I refresh the page, the image is requested if I'm not a visitor.

Context: products created and images imported from data files in a custom module

Image import:

<record id="product_product_1" model="product.product">
    <field name="image" type="base64" file="some_module/static/img/products/038.png"/>
</record>

Behavior: When I refresh the page, the image is always requested.

Expected behavior: Do not request the image if the image is the same.

Do I miss something here ?