All my Apple devices seem to get incremental numbers after their names.
e.g. iPhone (4), MacBook (127), etc. (They all have unique names, I just used the product names here as an example).
I read around and there seems to be some indication that it’s related to DHCP, though I’m not entirely sure how. Even though it’s most likely a client-side issue (on the devices), apparently not all routers will trigger this behaviour.