You may run several nodes if they are in the same /24 subnet of public IPs, but they will be treated as a one big node for uploads, and as a separate ones for downloads, repair and audit traffic and uptime checks: we want to be decentralized as much as possible.
Each new node must be vetted, while vetting the node can accept only 5% of the customers traffic until got vetted. To be vetted on the satellite the node should pass 100 audits from it. For the one node in the /24 subnet of public IPs it should take at least a month.
Several vetting nodes may have a longer vetting period, because they would share the ingress, so each would have less data and less audits.
Thus it’s recommended to start the second node only when the previous one almost full or at least vetted.