We've edited the UI so that you can see the pictures of both people assigned for an action. You are able to add multiple assignees by adding an assignee as normal then selecting the Multiple button. Check the people you would like to assign the task to and click Assign.
You can also create a separate action card for each assignee instead of having them on one shared card. To do so, just check the box next to Assign separate action for each assignee and click Assign.