Referencing another sheet in Google Sheet with conditional formatting

Hi,

I have this test google sheet here: https://docs.google.com/spreadsheets...it?usp=sharing

There are two sheets, each with some words. In each sheet I'm using the following conditional formatting to display duplicates (the first instance of a duplicate is not shown):

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In sheet 1 I would also like to display duplicate values if they occur in Sheet 2 (with a different fill color)

So for example, the word "blackberry" is not a duplicate in Sheet1, but it occurs in Sheet2 as well. So I'd like to show "blackberry" as a duplicate in Sheet 1

How can I do that?
Thanks

Thanks very much