Objects contribute to final gathering even when their Casts Shadows and Receive Shadows settings are turned off (in the Render Stats section of the object’s Attribute Editor). This is useful when using objects for final gather occlusion. For more information on Render Stats, see Render Stats.

To avoid this, hide the object in Maya to make sure it does not contribute to final gathering. Alternatively, if exporting to mi, you can manually set finalgather off for that object.