Jon

Problem:
You are experiencing an issue where duplicates of your translated pages appear in your Yoast XML sitemap, despite having the WPML SEO plugin installed.
Solution:
We recommend deactivating all other plugins on your website except for WPML Multilingual CMS, WPML String Translation, WPML SEO, and Yoast SEO. After doing this, force Yoast to regenerate the sitemap by following the instructions here: https://yoast.com/help/sitemap-does-not-update/
Additionally, please provide us with the debug information to better understand your setup. You can find the instructions on how to do this here: https://wpml.org/faq/provide-debug-information-faster-support/

If this solution does not apply to your case, or if it seems outdated, we highly recommend checking related known issues at https://wpml.org/known-issues/, verifying the version of the permanent fix, and confirming that you have installed the latest versions of themes and plugins. Should you need further assistance, please open a new support ticket at WPML support forum.