"Saint Francis" is a compound noun, meaning, 'saint' becomes part of the name.
therefore, if we're referring to two different persons, we can either use "Saints Francis" or "Saint Francises", but never both in plural form.
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In analogy, if we have Fr. Clement Distura and Fr. Clement Fungot:
"Frs. Clement" OR "Fr. Clements" is correct.
Of course, we would normally say, "Frs. Distura and Fungot" because this is clearer. But in the case of "St. Francis" where the modifier "saint" becomes an integral part of the name, only one is pluralized in form.