Double chat

Hii… i`m sori before if my englsih bad,

I want to asked about my spark, i have 2 user that had almost same name : made and ade. When i chat using spark with user made automaticly user ade can see my chat with user made. How can this be when i chat with user made but user ade can see my chat, it also with user gunani and ani. How to solve this problems? thank`s before