On the face of it this would appear to be a glitch of some kind. The only way that this could be forced to happen is if the KLM booking has a security element added to it to allow retrieval by BA. This is procedurally unlikely but technically possible. If BA had make the booking for you in one of their offices, for example, it would be retrievable, or if KLM added the element.
I would need the full booking details (record locator or pax name) to retrieve it. Obviously you don't want that displayed to the world, but if you want me to look at it and give you an explanation you can PM me.