When a sentence has two nouns but only one pronoun then only one of the nouns can be connected to the antecedent?

No, that is not true. The antecedent can be one noun, or two or more nouns.

For example:

Jack and Jill went up the hill carrying a pail with them. (the antecedent for the pronoun 'them' is the two nouns, Jack, Jill)

I have Apple, cherry, and lemon. Which one would you like? (there is no antecedent for the pronoun 'I'; the antecedents for the indefinite pronoun 'one' are the nouns Apple, cherry, lemon)