Hi Sunil,
What you have described is normal system behaviour. You will be able to see the Equipments in the Object list item tab of your Maintenance plan in the ObjectsTab of Maintenance Order. Go to the Order (IW32) created on your equipment P1234 through this plan and see in the Objects tab. You;ll find these Equipments. But you will not get anything out of IW38 if you query with equipments inside the Object list item tab of the Plan.
Jogeswara Rao K