By who's authority should the word "who's" be spelled "whose" and not "who's"?
In all seriousness, it's interesting to see how the live language is diverging from the rules. The dual ending "-ayim" is supposed to be used with the singular stem: nekuda(-t) - giving nekudatayim "two dots", and likewise shnatayim "two years", dakatayim "two minutes", etc. But in practice, speakers classify dual as plural and use the form with both plural and dual endings: nekudotayim, dakotayim
In all seriousness, it's interesting to see how the live language is diverging from the rules. The dual ending "-ayim" is supposed to be used with the singular stem: nekuda(-t) - giving nekudatayim "two dots", and likewise shnatayim "two years", dakatayim "two minutes", etc. But in practice, speakers classify dual as plural and use the form with both plural and dual endings: nekudotayim, dakotayim