diff --git a/app/models/repository.rb b/app/models/repository.rb
index a9d0922ba0..7ed9d6d880 100644
--- a/app/models/repository.rb
+++ b/app/models/repository.rb
@@ -23,7 +23,7 @@ class Repository < ApplicationRecord
   MEDIA_DIR = 'media'.freeze
 
   validates :name, presence: true, uniqueness: { case_sensitive: false }
-  validates :remote, presence: true
+  validates :remote, presence: true, uniqueness: { case_sensitive: false }
 
   validate :repo_is_accessible, on: :create
 
diff --git a/db/migrate/20231107160330_add_unique_to_repository_remote.rb b/db/migrate/20231107160330_add_unique_to_repository_remote.rb
new file mode 100644
index 0000000000..82c57dec43
--- /dev/null
+++ b/db/migrate/20231107160330_add_unique_to_repository_remote.rb
@@ -0,0 +1,5 @@
+class AddUniqueToRepositoryRemote < ActiveRecord::Migration[7.1]
+  def change
+    add_index :repositories, :remote, unique: true
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index c7a60a2e37..71cab76545 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.1].define(version: 2023_10_26_075353) do
+ActiveRecord::Schema[7.1].define(version: 2023_11_07_160330) do
   create_table "active_storage_attachments", charset: "utf8mb4", collation: "utf8mb4_unicode_ci", force: :cascade do |t|
     t.string "name", null: false
     t.string "record_type", null: false
@@ -396,6 +396,7 @@
     t.index ["judge_id"], name: "index_repositories_on_judge_id"
     t.index ["name"], name: "index_repositories_on_name", unique: true
     t.index ["path"], name: "index_repositories_on_path", unique: true
+    t.index ["remote"], name: "index_repositories_on_remote", unique: true
   end
 
   create_table "repository_admins", charset: "utf8mb4", collation: "utf8mb4_unicode_ci", force: :cascade do |t|
diff --git a/db/seeds.rb b/db/seeds.rb
index 070f80080e..a1396cd274 100644
--- a/db/seeds.rb
+++ b/db/seeds.rb
@@ -276,6 +276,9 @@ def fill_series_with_realistic_submissions(s)
   puts activity_repo.errors.full_messages unless activity_repo.valid?
   activity_repo.process_activities
 
+  # remote must be unique for the repository, and we want to clone it again
+  activity_repo.update!(remote: '-')
+
   big_activity_repo = Repository.create name: 'A lot of python activities', remote: 'git@github.com:dodona-edu/example-exercises.git', judge: python_judge, allowed_courses: courses
   Delayed::Worker.delay_jobs = true
   Dir.glob("#{big_activity_repo.full_path}/*")
diff --git a/test/controllers/repositories_controller_test.rb b/test/controllers/repositories_controller_test.rb
index 8c80b40ba1..0bc14179a7 100644
--- a/test/controllers/repositories_controller_test.rb
+++ b/test/controllers/repositories_controller_test.rb
@@ -200,6 +200,8 @@ class RepositoryGitControllerTest < ActionDispatch::IntegrationTest
     @remote.update_json('echo/config.json', 'make echo private') do |config|
       config.update 'access' => 'private'
     end
+
+    @second_remote = local_remote('exercises/lasagna')
   end
 
   def find_echo
@@ -222,16 +224,16 @@ def find_echo
     user = users(:staff)
     judge = create :judge, :git_stubbed
     sign_in user
-    post repositories_path, params: { repository: { name: 'test', remote: @remote.path, judge_id: judge.id } }
+    post repositories_path, params: { repository: { name: 'test', remote: @second_remote.path, judge_id: judge.id } }
   end
 
   test 'should email during repository creation' do
     user = users(:staff)
     judge = create :judge, :git_stubbed
     sign_in user
-    @remote.update_file('echo/config.json', 'break config') { '(╯°□°)╯︵ ┻━┻' }
+    @second_remote.update_file('exercises/extra/echo/config.json', 'break config') { '(╯°□°)╯︵ ┻━┻' }
     assert_difference 'ActionMailer::Base.deliveries.size', +1 do
-      post repositories_path, params: { repository: { name: 'test', remote: @remote.path, judge_id: judge.id } }
+      post repositories_path, params: { repository: { name: 'test', remote: @second_remote.path, judge_id: judge.id } }
     end
   end