Is it possible to address two LED Bar Graphs to two different digital pins (D5 and D7, for example)?
Yes.
You can have as many as will fit on your board and within the output range of your power source.
Bare in mind they are 4 pin sensors, so you need to skip a socket, eg. D5, D7, D9
They are not I2C displays. They and are individually addressable with a data + clock.
The sensors appear to be chainable based on the IO pins on the sides of the board.
I could not find a working example.
It should work similar to the Chainable RGB LED, where the output of the first sensor goes in to the input of the next.
The driver IC MY9221 seems to support it too.
Just need to find / create a working example and contribute it to the Github repo.