FORD 2004 Explorer v.1 - Manual (Page 135)

Your vehicle has LATCH anchors for child seat installation at the seating
positions marked with the child seat symbol:
Never attach two LATCH child safety seats to the same anchor.
In a crash, one anchor may not be strong enough to hold two
child safety seat attachments and may break, causing serious injury or
death.
2004 Explorer (exp)
Owners Guide (post-2002-fmt)
USA English (fus)
Seating and Safety Restraints
135