Tell us about your environment
Spigot 1.8.8
ViaVersion 2.0.4
BanManager 5.13.1
5 Servers
MySQL 5.6
Offline Mode

Describe your issue:
When you put "broadcastOnSync: true" inside the config, any ban issued in the source server will be broadcasted twice: one when the ban is issued and one when the ban is synced.

How to replicate:
Put "broadcastOnSync: true" in the config, reload/restart, then do "/ban Test test".