Fix an issue with posts duplicated in Discover

[kean]

Description

Fixes CMM-764: Reader: posts in Discover are duplicated

Testing instructions

I tested by duplicated a post in a mock response.

Before / After

[sonarqubecloud]

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[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Configuration	Release-Alpha
	Build Number	29895
	Version	PR #25015
	Bundle ID	org.wordpress.alpha
	Commit	535e60b
	Installation URL	1ti8q6ru4h8k8

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[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Configuration	Release-Alpha
	Build Number	29895
	Version	PR #25015
	Bundle ID	com.jetpack.alpha
	Commit	535e60b
	Installation URL	40q0plbrjjlv8

Automatticians: You can use our internal self-serve MC tool to give yourself access to those builds if needed.