Considering that what you are using are [toggle buttons](https://material.io/guidelines/components/buttons.html#buttons-toggle-buttons), if you don't want any of the two options to be selected then you could present them:

 - without any option predefined
 - with the possibility to unselect both buttons (adding an extra note to clarify this possibility or an *(optional)* next to the label)

[![enter image description here][1]][1]



  [1]: https://i.sstatic.net/6W3J3.png