I wonder can Appleseed use multiple machines to render simultaneously like Mitsuba?
Not on its own.
You would need a render farm software with a control script setting frame range, job command etc. The render manager then calls the command line renderer (appleseed-cli) and distributes the individual render frames across the multiple machines.
A free, open source render farm manager which is known to work with appleseed is Afanasy
Here is an example Python script for Afanasy to control rendering of an appleseed-Gaffer scene under Linux. It serves as a template to guide setting up a control-script.
Note: the reference to xvfb (the X virtual framebuffer) in lines 8 and 24 is not necessary on workstations with its own graphics cards.