The literary problems with the two rock episodes in Exodus and Numbers open us to the midrashic reflections on the Moshe Rabeinu’s anxiety prior to striking the rock.

For Rashi and others they were 2 separate historical episodes, for Bechor Shor  however,  two stories with similar content refer to a single event. 

The placing of the staff on the rock precipitates his rage and midrashic shame (woe is to me, maybe water will not issue and i will face my shame) 

which allows us to explore the psychic meaning of the rod/serpent in producing both blood and water:  from the first scene by the Burning Bush through the first plague to our two episodes the staff signifies the uncanny
unresolved issues that from the very ambivalence of his early infant abandonment and split identity.