Does the renewed understanding of Sheikh Al-Islam Ibn Taymiyyah's text regarding the multiplicity of eternals resolve the issue, and is the questioner's statement, "whether the existence of two necessary beings is impossible or possible rationally, it will not add anything; because there is no necessary being except His ذات سبحانه (His ذات, glory be to Him)," correct on the assumption of the impossible?

The questioner's understanding of Sheikh Al-Islam Ibn Taymiyyah's statement is incorrect. Ibn Taymiyyah holds that there is no objection to the multiplicity of "the Necessary" (Al-Wajib) or "the Pre-eternal" (Al-Qadim) if what is meant by them is that which has no beginning to its existence, and this includes the Essence and the Attributes. This is in contrast to the Pre-eternal who is the Creator of everything, for He is One. The multiplicity that is impermissible is for there to exist an ancient essence that is necessary by itself alongside Allah Almighty. Assuming two Necessaries in existence contradicts the meaning of the Necessary Existent, who is He whose existence is from His very Self and who needs nothing, and this applies only to Allah alone. Such complex issues should not be excessively delved into by beginners in the pursuit of knowledge.