diff --git a/lib/tasks/deployment/20220405092317_remove_duplicate_attestations.rake b/lib/tasks/deployment/20220405092317_remove_duplicate_attestations.rake
new file mode 100644
index 000000000..c0dfbc54a
--- /dev/null
+++ b/lib/tasks/deployment/20220405092317_remove_duplicate_attestations.rake
@@ -0,0 +1,25 @@
+namespace :after_party do
+  desc 'Deployment task: remove_duplicate_attestations'
+  task remove_duplicate_attestations: :environment do
+    dossier_ids = Attestation
+      .group(:dossier_id)
+      .count
+      .filter { |_, attestation_count| attestation_count > 1 }
+      .map(&:first)
+
+    dossier_ids.each do |dossier_id|
+      current_attestation, *old_attestations = Attestation.where(dossier_id: dossier_id).order(created_at: :desc)
+
+      old_attestations.each do |old|
+        if current_attestation.created_at < old.created_at
+          raise "something odd, old attestation #{old.id} is newer than the current attestation #{current_attestation.id}"
+        end
+
+        old.destroy
+      end
+    end
+
+    AfterParty::TaskRecord
+      .create version: AfterParty::TaskRecorder.new(__FILE__).timestamp
+  end
+end