With the Narrator enabled, go to the world selection screen and click a world name. The Narrator says "Selected" twice before announcing the info about the world.

The game is probably grabbing "Selected: %s" from the string narrator.select, and only then replacing the %s with the string narrator.selected.world, which also begins with "Selected". The fix is to either remove the replacement in the first string and use the second one directly, or to remove the world "Selected" in the second string.

Related to MC-147869.