Get the app "InstaCollageFree"
Select the two photo frame
Choose from either your camera roll or take one
Select the photo you want twice
Make sure all the slide bars are down, and you have the "no frame" selected
Adjust pictures how you want and click "Rotate/Mirror"
Rotate them and mirror them however you think looks best
Save and you have a mirrored photo(: I hope this helped
- Insta Collage Free