You know, without flipping one and getting unexpected results, and then flipping the other and getting even worse unexpected results, and then just deleting them both and recreating them as you intend.
1. Suppress both mates.
2. Flip one mate.
3. Flip second mate.
4. Unsuppress both mates.
If you wanna get tricky, add the series indicator "..." between step 3 and 4 to inject however many instances as you desire.
SolidworksModeling And Assemblies