Is it ok to wear shoes of different sizes in each leg? Would it affect her posture or gait ?

My 3 year old was tip-toeing with her left leg, so she had to wear serial plasters for 4 weeks and now she needs to wear an orthotic or the dynamic AFO on her left leg. But when she wears the AFO inside the joggers, the sizes dont fit well. I tried many pairs, her right foot fits well into US size 12, but her left foot fits properly only in size 13( as she needs to wear her AFO also). Is it ok to wear shoes of different sizes in each leg? Would it affect her posture or gait ?