Can 2 20mg Fluoxetine Capsules Be Taken Instead Of 1 40mg Capsule?

I'm on fluoxetine capsules for recurrent depression, and SAD disorder too. My GP increased my dose from 20mg a day to 40mg a day. I have run out of my 40mg capsules but have a lot of 20mg capsules left. I next see my GP on Friday, so can I just take two 20mg capsules until I next see him, or should I push for an earlier appointment. Thanks.