#More than one caster can benefit from hunter's mark on the same target

Hunter's mark only benefits the caster of the spell. There is no overlapping effects to combine. From the text for hunter's mark I have highlighted ever reference to the creature that gains the effects:

You choose a creature you can see within range and mystically mark it as your quarry. Until the spell ends, you deal an extra 1d6 damage to the target whenever you hit it with a weapon attack, and you have advantage on any Wisdom (Perception) or Wisdom (Survival) check you make to find it. If the target drops to 0 hit points before this spell ends, you can use a bonus action on a subsequent turn of yours to mark a new creature.

The spell has no effect on the quarry, only on the caster. Since the two casters are different, these effects do not overlap. Therefore the rules on combining effects do not apply.

More than one caster can benefit from hunter's mark on the same target

Hunter's mark only benefits the caster of the spell. There is no overlapping effects to combine. From the text for hunter's mark I have highlighted ever reference to the creature that gains the effects:

You choose a creature you can see within range and mystically mark it as your quarry. Until the spell ends, you deal an extra 1d6 damage to the target whenever you hit it with a weapon attack, and you have advantage on any Wisdom (Perception) or Wisdom (Survival) check you make to find it. If the target drops to 0 hit points before this spell ends, you can use a bonus action on a subsequent turn of yours to mark a new creature.

The spell has no effect on the quarry, only on the caster. Since the two casters are different, these effects do not overlap. Therefore the rules on combining effects do not apply.

#More than one caster can benefit from hunter's mark on the same target

Hunter's mark only benefits the caster of the spell. There is no overlapping effects to combine. From the text for hunter's mark I have highlighted ever reference to the creature that gains the effects:

You choose a creature you can see within range and mystically mark it as your quarry. Until the spell ends, you deal an extra 1d6 damage to the target whenever you hit it with a weapon attack, and you have advantage on any Wisdom (Perception) or Wisdom (Survival) check you make to find it. If the target drops to 0 hit points before this spell ends, you can use a bonus action on a subsequent turn of yours to mark a new creature.

The spell has not effect on the quarry, only on the caster. Since the two caster's are different, these effects do not overlap. Therefore the rules on combining effects do not apply.

#More than one caster can benefit from hunter's mark on the same target

Hunter's mark only benefits the caster of the spell. There is no overlapping effects to combine. From the text for hunter's mark I have highlighted ever reference to the creature that gains the effects:

You choose a creature you can see within range and mystically mark it as your quarry. Until the spell ends, you deal an extra 1d6 damage to the target whenever you hit it with a weapon attack, and you have advantage on any Wisdom (Perception) or Wisdom (Survival) check you make to find it. If the target drops to 0 hit points before this spell ends, you can use a bonus action on a subsequent turn of yours to mark a new creature.

The spell has no effect on the quarry, only on the caster. Since the two casters are different, these effects do not overlap. Therefore the rules on combining effects do not apply.