Index: Core/Common/test/Core.Common.TestUtil.Test/RandomExtensionsTest.cs
===================================================================
diff -u -rcaf283454626efc376c01fc0e54ab4c902aaf1df -r849b66d3e1542c3b2972bf84da7d62d1f81fa02d
--- Core/Common/test/Core.Common.TestUtil.Test/RandomExtensionsTest.cs	(.../RandomExtensionsTest.cs)	(revision caf283454626efc376c01fc0e54ab4c902aaf1df)
+++ Core/Common/test/Core.Common.TestUtil.Test/RandomExtensionsTest.cs	(.../RandomExtensionsTest.cs)	(revision 849b66d3e1542c3b2972bf84da7d62d1f81fa02d)
@@ -153,7 +153,7 @@
         [Test]
         [TestCase(0, TestEnum.ValueThree)]
         [TestCase(1, TestEnum.ValueOne)]
-        public void NextEnumValue_TypeIsEnum_ReturnsEnum(int seed, TestEnum expectedFirstCallResult)
+        public void NextEnumValue_TypeIsEnum_ReturnsEnum(int seed, TestEnum expectedResult)
         {
             // Setup
             var random = new Random(seed);
@@ -162,7 +162,7 @@
             var result = random.NextEnumValue<TestEnum>();
 
             // Assert
-            Assert.AreEqual(expectedFirstCallResult, result);
+            Assert.AreEqual(expectedResult, result);
         }
 
         [Test]
@@ -251,9 +251,9 @@
         }
 
         [Test]
-        [TestCase(0, 1)]
-        [TestCase(1, 0)]
-        public void NextEnumValueWithEnumValues_WithValidArguments_ReturnsRandomEnum(int seed, int expectedIndex)
+        [TestCase(0, TestEnum.ValueThree)]
+        [TestCase(1, TestEnum.ValueTwo)]
+        public void NextEnumValueWithEnumValues_WithValidArguments_ReturnsRandomEnum(int seed, TestEnum expectedResult)
         {
             // Setup
             var random = new Random(seed);
@@ -267,7 +267,7 @@
             object randomItem = random.NextEnumValue(enumValues);
 
             // Assert
-            Assert.AreEqual(enumValues[expectedIndex], randomItem);
+            Assert.AreEqual(expectedResult, randomItem);
         }
 
         public enum TestEnum
Index: Ringtoets/Integration/test/Ringtoets.Integration.IO.Test/Helpers/IdentifierGeneratorTest.cs
===================================================================
diff -u -rc2e1b46490dfdc848647c515e3ea04c1f7f69535 -r849b66d3e1542c3b2972bf84da7d62d1f81fa02d
--- Ringtoets/Integration/test/Ringtoets.Integration.IO.Test/Helpers/IdentifierGeneratorTest.cs	(.../IdentifierGeneratorTest.cs)	(revision c2e1b46490dfdc848647c515e3ea04c1f7f69535)
+++ Ringtoets/Integration/test/Ringtoets.Integration.IO.Test/Helpers/IdentifierGeneratorTest.cs	(.../IdentifierGeneratorTest.cs)	(revision 849b66d3e1542c3b2972bf84da7d62d1f81fa02d)
@@ -65,7 +65,7 @@
         }
 
         [Test]
-        public void GetNewId_IdAlreadyUsed_ReturnsExpectedValue()
+        public void GetNewId_PrefixAlreadyUsed_ReturnsExpectedValue()
         {
             // Setup
             const string prefix = "prefix";
@@ -83,7 +83,7 @@
         }
 
         [Test]
-        public void GivenIdGeneratorWithPrefixEntries_WhenGetNewIdCalledWithDifferentPrefix_ThenExpectedValuesReturned()
+        public void GetNewId_NewPrefix_ReturnsExpectedValues()
         {
             // Given
             const string prefix = "prefix";
@@ -95,6 +95,25 @@
             const string newPrefix = "NewPrefix";
 
             // When
+            string newPrefixId = generator.GetNewId(newPrefix);
+
+            // Then
+            Assert.AreEqual($"{newPrefix}.0", newPrefixId);
+        }
+
+        [Test]
+        public void GivenIdGenerator_WhenMultiplePrefixesUsed_ThenReturnsExpectedValues()
+        {
+            // Given
+            const string prefix = "prefix";
+            var generator = new IdentifierGenerator();
+
+            // Precondition
+            Assert.AreEqual($"{prefix}.0", generator.GetNewId(prefix));
+
+            const string newPrefix = "NewPrefix";
+
+            // When
             string oldPrefixId = generator.GetNewId(prefix);
             string newPrefixId = generator.GetNewId(newPrefix);