Multiple Nodes single key

Hi, i have two nodes, different ISPs and different residential locations… which is better?

  1. multiple nodes using the same private key

or

  1. multiple nodes different private key?

I have a conclusion that a multiple nodes with single key will make your node identity (public key) much more available (liveness) in case an ISP is down or other node got disconnected… its like the “cloud regions” wherein when one ISP is down the service is still up… so whats your opinion or setup?