Tasks assigned to someone else showing on my planned list.

I have a couple of shared lists that my partner and I use to assign tasks that we need each other to complete. I assign a task to him – he adds a due date to it depending on when he can fit it into his schedule and vice versa. 

We switched over from Wunderlist to To Do — they both seemed to function pretty similarly so it seemed like the perfect switch with Wunderlist shutting down.

But there's 1 issue I'm having... tasks assigned to HIM show up on MY planned list when he adds his due date. Is there a way to stop his tasks from showing up on my list?