Since you aren't using the VFS cache, the rclone rcd is almost stateless and should load balance OK I think. Though if you are using async polling then that might not work so well unless you have persistent connections. It will certainly work Live and standby.
Rclone isn't built to be 'stateful' so if you have 2 instances running, they can't act as a 'both on' type persisting across if one goes down like a stateful failover on a firewalll cluster/load balancer/etc.
You can load balance them and do a primary/standby but anything in flight on the primary would need to be replaying on the standby.
I'd imagine you can also have a VM that would failover from one host to another, but the same consideration I think would apply as you'd have to replay things.