Changing the language pairs for suggestions triggers suggestions to load. When the language pairs are switched quick enough, that results in suggestions from different languages to appear in a single list.
This can happen in the following usecase: Initial language pair is "English>French", but the user is interested in "Spanish>Italian" suggestions. That requires the user to make two changes (adjust source and target language). If that is done quick enough, The user may get suggestions combining "Spanish>French" and "Spanish>Italian" items.