In historical polemics the objection from multiple eternal realities was compared to the discourse about three hypostases (aqānīm). The challenge was that affirming eternal attributes allegedly permits several eternally existing subjects.
The reply denies that knowledge, life, or other attributes are independently subsisting persons or essences. Multiple eternal attributes of one essence therefore do not entail three or more autonomous gods.
This is a classical polemical analogy, not a complete description of Christian theological doctrines. The relevant logical point is the distinction between an attribute's being real and its being an independent subject.