PROJ TNUM

defineprojectile <tile number> PROJ_TNUM <number>

The maximum number of trails that an individual projectile can spawn. By default, RPG (non-hitscan) type projectiles will spawn trails even if TNUM is not set. But bullet type (hitscan) projectiles will not spawn any trails unless TNUM is given a non-zero value.

The way it works, is that if TNUM value is set to 2, then it will spawn 2 of the sprites on the same location. The default value is 1 if a trail is set for the projectile.