Hi @ELI,
After checking our logs, it seems you had the XP Decay feature enabled during the time of the 'duplicate' level ups. As you may know XP decay removes ("decays") XP from all users after a set interval. From at least July 30, 2024 until August 21, 2024, this system was enabled at some point (it seems several users have been activating and deactivating it within this period).
What was probably happen is that users would level up, then some time later XP decay would trigger, putting them below the minimum amount of XP required for a certain level, and then would gain back that XP again, and get the level up messages for the same level. XP Decay removing XP is expected behavior.