This was caused by bug in 7.1.0 that is supposedly fixed in incoming 7.1.0.2 Engineering deleted the second pool an re-added the nodes to the first pool using internal use disi command
We upgraded our (4x iq_32000x-ssd) with 3 more X400 nodes, with exactly the same configuration (disk, memory). After I added the new nodes I realized that they went to a new node pool,  which is not what we wanted. Now we have a pool with 4 nodes and another with 3 nodes, and each one is protected with 2:1 , doubling the cluster overhead (correct me if my overhead logic is wrong).  I opened a case and they are telling me that merging these node pools is impossible since the nodes have different config IDs:  nyst0087-1# isi_for_array isi_hw_status|grep -i config | sort nyst0087-1:  Config: 851-0105-02 nyst0087-2:  Config: 851-0105-02 nyst0087-3:  Config: 851-0105-02 nyst0087-4:  Config: 851-0105-02 nyst0087-5:  Config: 851-0074-01 nyst0087-6:  Config: 400-0029-01 nyst0087-7:  Config: 400-0029-01 nyst0087-8:  Config: 400-0029-01  Is this true ?  (We do not have SmartPools licenese, and with this configuration we do not need it)
Upgraded cluster, cannot merge node pools