Hi,
If you can use the AMS5812 for your application I would recommend using 2 of those so you do not have to implement code for two different sensors.
It is not possible to mount 2 AMS5915 sensors to the same bus since they have a fixed I2C address as you mentioned. The only way to use 2 AMS5915 sensors would be to use an I2C bus multiplexer like these:
Let us know if you have any other questions.
Thank you,
Travis Elliott