diff --git a/modules/store/spec/reducer_creator.spec.ts b/modules/store/spec/reducer_creator.spec.ts
index ff2a2d4e7a..c7593128f8 100644
--- a/modules/store/spec/reducer_creator.spec.ts
+++ b/modules/store/spec/reducer_creator.spec.ts
@@ -86,6 +86,23 @@ import {on} from './modules/store/src/reducer_creator';
         state = fooBarReducer(state, bar({ bar: 54 }));
         expect(state).toEqual(['[foobar] FOO', '[foobar] BAR']);
       });
+
+      it('should support "on"s to have identical action types', () => {
+        const increase = createAction('[COUNTER] increase');
+
+        const counterReducer = createReducer(
+          0,
+          on(increase, state => state + 1),
+          on(increase, state => state + 1)
+        );
+
+        expect(typeof counterReducer).toEqual('function');
+
+        let state = 5;
+
+        state = counterReducer(state, increase());
+        expect(state).toEqual(7);
+      });
     });
   });
 });
diff --git a/modules/store/src/reducer_creator.ts b/modules/store/src/reducer_creator.ts
index ba22d2a93d..ce5ca0730d 100644
--- a/modules/store/src/reducer_creator.ts
+++ b/modules/store/src/reducer_creator.ts
@@ -232,7 +232,14 @@ export function createReducer<S, A extends Action = Action>(
   const map = new Map<string, ActionReducer<S, A>>();
   for (let on of ons) {
     for (let type of on.types) {
-      map.set(type, on.reducer);
+      if (map.has(type)) {
+        const existingReducer = map.get(type) as ActionReducer<S, A>;
+        const newReducer: ActionReducer<S, A> = (state, action) =>
+          on.reducer(existingReducer(state, action), action);
+        map.set(type, newReducer);
+      } else {
+        map.set(type, on.reducer);
+      }
     }
   }