sql server active active configuration with same database names
You have two different clusters sharing the nodes, both clusters in having one active and one passive node. The names and resources on each cluster are completely independent from the names and resources on the other cluster. So you can safely add Dnb_E and each cluster. On failover the node running now the active node of both clusters will start OK, since the Db_E on the cluster A is different from Db_E on cluster B. Notice that I intentionally avoided using the name 'instance'.

Using the misleading 'active-active' nomenclature just leads down the thinking that you somehow share resources between the two clusters. Calling this configuration 'active-active' is strongly discouraged.