diff -u b/core/lib/Drupal/Core/Entity/EntityWithDirtyFieldsInterface.php b/core/lib/Drupal/Core/Entity/EntityWithDirtyFieldsInterface.php
--- b/core/lib/Drupal/Core/Entity/EntityWithDirtyFieldsInterface.php
+++ b/core/lib/Drupal/Core/Entity/EntityWithDirtyFieldsInterface.php
@@ -5,7 +5,7 @@
 /**
  * Interface for entities having fields that can become dirty.
  *
- * This interface extends the general fieldable entity interface. So that that
+ * This interface extends the general fieldable entity interface. So that
  * interface is not modified during the Drupal 8.x cycle.
  *
  * @todo Merge this interface with FieldableEntityInterface before Drupal 9.0.