Zaydun ibnu ʿālimin has an indefinite common noun as the second member; the required second proper name is missing, so the special omission rule does not apply.
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If the Second Item Is Not a Name
Tanwīn: Five Types, Their Function, and Omission
Zaydun ibnu ʿālimin has an indefinite common noun as the second member; the required second proper name is missing, so the special omission rule does not apply.