diff --git a/src/migrations/20210302080040-add-pk-to-client-instances.js b/src/migrations/20210302080040-add-pk-to-client-instances.js
index eecf9f887d..210f674638 100644
--- a/src/migrations/20210302080040-add-pk-to-client-instances.js
+++ b/src/migrations/20210302080040-add-pk-to-client-instances.js
@@ -3,6 +3,7 @@
 exports.up = function(db, cb) {
     db.runSql(
         `
+    DELETE FROM client_instances a USING client_instances b WHERE a.app_name = b.app_name AND a.instance_id = b.instance_id AND a.created_at < b.created_at;
     ALTER TABLE client_instances ADD PRIMARY KEY (app_name, instance_id);
   `,
         cb,
@@ -13,7 +14,7 @@ exports.down = function(db, cb) {
     db.runSql(
         `
         ALTER TABLE client_instances DROP CONSTRAINT client_instances_pkey;
-        DROP INDEX client_instance_pkey
+        DROP INDEX IF EXISTS client_instance_pkey
     `,
         cb,
     );