Implemented some enhancement requests

tests/non_reg/test_sheerka_display.py

@@ -2,6 +2,11 @@ from tests.TestUsingMemoryBasedSheerka import TestUsingMemoryBasedSheerka
 
 
 class TestSheerkaNonRegDisplay(TestUsingMemoryBasedSheerka):
+    @classmethod
+    def teardown_class(cls):
+        # At the end of the tests, sheerka singleton instance will be corrupted
+        # Ask for a new one
+        TestSheerkaNonRegDisplay.singleton_instance = None
 
     def test_i_can_display_results_when_return_values_processing_is_on(self, capsys):
         init = [
@@ -51,4 +56,20 @@ post      : None
 ret       : None
 vars      : []
 props     : {}
+"""
+
+    def test_i_can_display_multiple_success(self, capsys):
+        init = [
+            "def concept foo as 1",
+            "def concept foo as 2",
+        ]
+        sheerka = self.init_scenario(init)
+        capsys.readouterr()
+
+        sheerka.enable_process_return_values = True
+        sheerka.evaluate_user_input("foo")
+
+        captured = capsys.readouterr()
+        assert captured.out == """ReturnValue(who=evaluators.Concept, status=True, value=(1001)foo)
+ReturnValue(who=evaluators.Concept, status=True, value=(1002)foo)
 """