I have written the explanation a few times on duolingo but ill put it here too.
From my web programming experience the way this site is probably programmed is a lookup table / query system where when you hover over the word it looks for the definitions of that word or phrase in the database and it us up to you to pick the best definition.
This is just how a dictionary would work too if you were looking at it to understand a word. If you weren't sure what "peso" meant for example a dictionary might give "weight" and "unit of Chilean currency" but to say how heavy a man is only one of those is correct.
Similarly if you look up "match", as in the thing you set on fire, in the dictionary it might give you "fósforo" and "juego" but you would only put fósforo as the other one refers to a game / sport.
It would probably be very hard to change this quirk without them rewriting the entire way the site works.
Obviously i don't work for duolingo but this is why i think it happens like you say.