It all depends who was the original dream sharer. Leo does explain that the whole point of the totem and to keep it to yourself is so that you may recognise it in the dreams. Obviously Leo knew all about Mal's totem hence if Mal and Leo were in a dream conceived by Leo, he would have been able to replicate the totem behavior or atleast Leo's subconsious.
Also the totem specifically tells if you are in some one else's dream or not. it dosent apply something that totem holder dreams of and is a part of.
Also the totem specifically tells if you are in some one else's dream or not. it dosent apply something that totem holder dreams of and is a part of.