Should I Wear Inserts In Both Feet Or Just The Affected One For Plantar Fasciitis In One Foot?

I m a runner, and have plantars fasciitis. I had it once 9 years ago and the only thing that helped was wearing inserts. So, I m going to try that again. Do I need to wear both the left and right insert or can I wear it only in the right, where the pain is?