MongoDB Shard Zone Range Overlapping

I am configuring a test mongo setup with 2 shards, and I'm trying to add zone ranges to each shard: sh.updateZoneKeyRange('mydb.test', {id:MinKey,ts:MinKey}, {id:MaxKey,ts:1548787704000}, 'cold') sh.updateZoneKeyRange('mydb.test', {id:MinKey,ts:1548787704000}, {id:MaxKey,ts:MaxKey}, 'hot') First command runs fine, but second tells me: Zone range: { id: MinKey, ts: 1548787704000.0 } -->> { id: MaxKey, ts: MaxKey } on hot is overlapping with existing: { id: MinKey, ts: MinKey } -->> { id: MaxKey, ts: 1548787704000.0 } on cold I thought the maximum bounds were exclusive and minimum bounds inclusive?