[11:16:32] [Server thread/WARN]: [Duels] Task #1274 for Duels v1.0 generated an exception
java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:859) ~[?:1.7.0_71]
	at java.util.ArrayList$Itr.next(ArrayList.java:831) ~[?:1.7.0_71]
	at me.laekh.duels.duel.DuelManager$1.run(DuelManager.java:119) ~[?:?]
	at org.bukkit.craftbukkit.v1_7_R4.scheduler.CraftTask.run(CraftTask.java:71) ~[spigot.jar:git-Spigot-1649]
	at org.bukkit.craftbukkit.v1_7_R4.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:350) [spigot.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.MinecraftServer.v(MinecraftServer.java:641) [spigot.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.DedicatedServer.v(DedicatedServer.java:289) [spigot.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.MinecraftServer.u(MinecraftServer.java:584) [spigot.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.MinecraftServer.run(MinecraftServer.java:490) [spigot.jar:git-Spigot-1649]
	at net.minecraft.server.v1_7_R4.ThreadServerApplication.run(SourceFile:628) [spigot.jar:git-Spigot-1649]