When I am in a party and we go through a SRD together, I think sometimes the dungeon automatically split the loot with "Your Loot" and "Others' Loot," but last night we went through SRDs and any party member could loot every chest in its entirety. Am I misremembering that first part? Is that loot splitting system only in Group Dungeons?
Loot splitting is a part in every PvE activity that you do as a party. It may be the case that the party leader changed the loot settings to "free". This way everything can be picked up by everyone.
More likely it's a bug (at least I think it is) that occurs sometimes when multiple people open a chest at once even when the loot settings are NOT set to free.