Could a bump and indentation after Botox be leftover Voluma? Looking for second opinions. (photos)

The raised area you mentioned is more likely to be muscle than previously injected Voluma.  A year after treatment the Voluma would not have moved.  I suggest meeting with your injector to discuss your concerns.  

Botox relaxes muscle motion. It is mixed with saline and is very thin compared to the substance of Voluma which is viscous/thick and won't be pushed by the thin Botox liquid.The information provided in Dr. Shelton's answer is for educational purposes only and is not intended to constitute medical advice.  The information provided should not be relied upon as a substitute for consultations with a qualified health professional who may be familiar with your individual medical needs. 

Thank you for sharing your question and photograph.  If the bump was not present before this second round of Botox it is unlikely to be the Voluma and is more likely incomplete muscle paralysis after not receiving it in your lower forehead.  Hope this helps.