different between dubiety vs doubtfulness

English

dubiety (countable and uncountable, plural dubieties)

(uncountable) Doubtfulness.
(countable) A particular instance of doubt or uncertainty.
- 1843, Thomas Carlyle, Past and Present, book 2, ch. 2,
  And yet these grim old walls are not a dilettantism and dubiety; they are an earnest fact. It was a most real and serious purpose they were built for!

From Middle English doutefulnesse, dowtefulnesse, equivalent to doubtful +? -ness.

doubtfulness (usually uncountable, plural doubtfulnesses)

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