diff --git a/app/src/main/java/com/todoroo/astrid/service/Upgrade_12_4.kt b/app/src/main/java/com/todoroo/astrid/service/Upgrade_12_4.kt
index 9312fbb66..b1e4902e7 100644
--- a/app/src/main/java/com/todoroo/astrid/service/Upgrade_12_4.kt
+++ b/app/src/main/java/com/todoroo/astrid/service/Upgrade_12_4.kt
@@ -15,15 +15,16 @@ class Upgrade_12_4 @Inject constructor(
     private val upgraderDao: UpgraderDao,
 ) {
     internal suspend fun syncExistingAlarms() {
-        val existingAlarms = alarmDao.getActiveAlarms().map { it.task }
+        val existingAlarms = alarmDao.getActiveAlarms()
         upgraderDao.tasksWithVtodos().forEach { caldav ->
             val remoteTask = caldav.vtodo?.let(iCalendar::fromVtodo) ?: return@forEach
             remoteTask
                 .reminders
-                .onEach { alarm -> alarm.task = caldav.id }
-                .let { alarms -> alarmDao.insert(alarms) }
+                .filter { existingAlarms.find { e -> e.task == caldav.id && e.same(it) } == null }
+                .onEach { it.task = caldav.id }
+                .let { alarmDao.insert(it) }
         }
-        taskDao.touch(existingAlarms)
+        taskDao.touch(existingAlarms.map { it.task }.toSet().toList())
     }
 
     companion object {
diff --git a/app/src/main/java/org/tasks/data/Alarm.kt b/app/src/main/java/org/tasks/data/Alarm.kt
index b88268b21..5b24dc9e0 100644
--- a/app/src/main/java/org/tasks/data/Alarm.kt
+++ b/app/src/main/java/org/tasks/data/Alarm.kt
@@ -70,6 +70,12 @@ class Alarm : Parcelable {
         return "Alarm(id=$id, task=$task, time=$timestamp, type=$type, repeat=$repeat, interval=$interval)"
     }
 
+    fun same(other: Alarm) =
+        type == other.type &&
+                time == other.time &&
+                repeat == other.repeat &&
+                interval == other.interval
+
     override fun equals(other: Any?): Boolean {
         if (this === other) return true
         if (javaClass != other?.javaClass) return false
diff --git a/app/src/main/java/org/tasks/db/Migrations.kt b/app/src/main/java/org/tasks/db/Migrations.kt
index d2fec0fc6..0be765c2e 100644
--- a/app/src/main/java/org/tasks/db/Migrations.kt
+++ b/app/src/main/java/org/tasks/db/Migrations.kt
@@ -420,13 +420,13 @@ object Migrations {
             database.execSQL("ALTER TABLE `alarms` ADD COLUMN `repeat` INTEGER NOT NULL DEFAULT 0")
             database.execSQL("ALTER TABLE `alarms` ADD COLUMN `interval` INTEGER NOT NULL DEFAULT 0")
             database.execSQL(
-                "INSERT INTO `alarms` (`task`, `time`, `type`) SELECT `_id`, 0, $TYPE_REL_START FROM `tasks` WHERE `hideUntil` > 0 AND `notificationFlags` | $NOTIFY_AT_START"
+                "INSERT INTO `alarms` (`task`, `time`, `type`) SELECT `_id`, 0, $TYPE_REL_START FROM `tasks` WHERE `hideUntil` > 0 AND `notificationFlags` & $NOTIFY_AT_START = $NOTIFY_AT_START"
             )
             database.execSQL(
-                "INSERT INTO `alarms` (`task`, `time`, `type`) SELECT `_id`, 0, $TYPE_REL_END FROM `tasks` WHERE `dueDate` > 0 AND `notificationFlags` | $NOTIFY_AT_DEADLINE"
+                "INSERT INTO `alarms` (`task`, `time`, `type`) SELECT `_id`, 0, $TYPE_REL_END FROM `tasks` WHERE `dueDate` > 0 AND `notificationFlags` & $NOTIFY_AT_DEADLINE = $NOTIFY_AT_DEADLINE"
             )
             database.execSQL(
-                "INSERT INTO `alarms` (`task`, `time`, `type`, `repeat`, `interval`) SELECT `_id`, ${HOURS.toMillis(24)}, $TYPE_REL_END, 6, ${HOURS.toMillis(24)} FROM `tasks` WHERE `dueDate` > 0 AND `notificationFlags` | $NOTIFY_AFTER_DEADLINE"
+                "INSERT INTO `alarms` (`task`, `time`, `type`, `repeat`, `interval`) SELECT `_id`, ${HOURS.toMillis(24)}, $TYPE_REL_END, 6, ${HOURS.toMillis(24)} FROM `tasks` WHERE `dueDate` > 0 AND `notificationFlags` & $NOTIFY_AFTER_DEADLINE = $NOTIFY_AFTER_DEADLINE"
             )
             database.execSQL(
                 "INSERT INTO `alarms` (`task`, `time`, `type`) SELECT `_id`, `notifications`, $TYPE_RANDOM FROM `tasks` WHERE `notifications` > 0"