Do a root search using the example given in the Search Helps: root:ζαω
(the same thing happens with other roots as well.)
Note the highlights in the picture below. Some verses/results have two entries, one of which has the root ζαω, and one of which has a different root (an article, or another lemma altogether).

Is this a bug or is it by design? If it is by design then what causes the double entries and what is their purpose?
If it is by design then it is definitely confusing and some type of explanatory note would be helpful.