Filter out duplicate student ids when loading work (#455)

## Status

- Closes _add issue numbers or delete_
- Related to _add issue numbers or delete_

## Points for consideration:

- Security
- Performance

## What's changed?

_Description of what's been done - bullets are often best_

## Steps to perform after deploying to production

_If the production environment requires any extra work after this PR has
been deployed detail it here. This could be running a Rake task, a
migration, or upgrading a Gem. That kind of thing._

Author: loiswells97

app/models/project.rb

@@ -31,7 +31,7 @@ class Project < ApplicationRecord
 
   def self.users(current_user)
     school = School.find_by(id: pluck(:school_id))
-    SchoolStudent::List.call(school:, token: current_user.token, student_ids: pluck(:user_id))[:school_students] || []
+    SchoolStudent::List.call(school:, token: current_user.token, student_ids: pluck(:user_id).uniq)[:school_students] || []
   end
 
   def self.with_users(current_user)