Join returning seemingly too many (duplicate) rows.

-- Use a JOIN to select all patrons with outstanding books. Select their first name and email address.
SELECT p.first_name, p.email FROM patrons as p 
INNER JOIN loans as l ON p.id = l.patron_id
WHERE l.returned_on IS NULL;

1) patron names are being returned multiple times, once for each row in loans where that patron has an outstanding loan (where returned_on IS NULL). It doesn't seem like this can possibly be the results set we want (confusing duplicates included). Can the JOIN or WHERE be written differently to have each relevant patron name returned just once?

2) Adding DISTINCT seems to solve the problem of multiple, duplicate rows...

SELECT DISTINCT  p.first_name, p.email FROM patrons as p 
INNER JOIN loans as l ON p.id = l.patron_id
WHERE l.returned_on IS NULL;

BUT... is this "fix" legitimate/correct? If this were a real-life table with thousands of rows, I wouldn't be able to visually check and confirm the result. What if the patrons table had multiple "Dave"s (for example), who had oustanding loans, then I'm pretty sure the DISTINCT "trick" would NOT work, is this correct?

This version will give ALL the patron names needed (even if/when there are duplicate first names), BUT it selects the id field from patrons, which we don't really want. This is the closest to seemingly-correct query that I can get, so far.

SELECT DISTINCT  p.id, p.first_name, p.email FROM patrons as p 
INNER JOIN loans as l ON p.id = l.patron_id
WHERE l.returned_on IS NULL;

3) Is there a place we can go to see some possible "correct answers" for these challenges/exercises?