Fixed duplication glitch.

HostageArena is configured for 3 Hostages to spawn, but there was a
duplication glitch that caused 6 hostages to spawn instead.

The glitch was caused by setting the respawn time (rs) greater than zero.

Normally, BattleArena will spawn the villagers BEFORE onStart(), but if
the respawn time is set, then BattleArena will spawn them again AFTER
onStart().