Both spelling's appear to be acceptable.
blog.oxforddictionaries.com/2017/08/03/auntie-and-aunty/
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Cerebus Sticky! Sticky! Stick! Stick!, Wed 29 Nov 2017, 14:03,
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I see you like apostrophe`s
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My Name was saying these words inside your head on, Wed 29 Nov 2017, 14:27,
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I see you spotted my Tab bait.
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Cerebus Sticky! Sticky! Stick! Stick!, Wed 29 Nov 2017, 14:29,
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That was "unnece's'sary"
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evil_andy Stick stick stick stick sticky sticky stick stick, Wed 29 Nov 2017, 16:09,
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