diff --git a/src/System.Management.Automation/engine/Modules/ModuleIntrinsics.cs b/src/System.Management.Automation/engine/Modules/ModuleIntrinsics.cs
index f40b4595a38..2e71fcda98d 100644
--- a/src/System.Management.Automation/engine/Modules/ModuleIntrinsics.cs
+++ b/src/System.Management.Automation/engine/Modules/ModuleIntrinsics.cs
@@ -948,7 +948,11 @@ private static string SetModulePath()
 #if !UNIX
                 // If on Windows, we want to add the System32 Windows PowerShell module directory
                 // so that Windows modules are discoverable
-                newModulePathString += Path.PathSeparator + GetWindowsPowerShellPSHomeModulePath();
+                string windowsPowerShellModulePath = GetWindowsPowerShellPSHomeModulePath();
+                if (!newModulePathString.Contains(windowsPowerShellModulePath, StringComparison.OrdinalIgnoreCase))
+                {
+                    newModulePathString += Path.PathSeparator + windowsPowerShellModulePath;
+                }
 #endif
 
                 // Set the environment variable...
diff --git a/test/powershell/Modules/Microsoft.PowerShell.Core/CompatiblePSEditions.Module.Tests.ps1 b/test/powershell/Modules/Microsoft.PowerShell.Core/CompatiblePSEditions.Module.Tests.ps1
index 3861c1b7c0a..767679c82e2 100644
--- a/test/powershell/Modules/Microsoft.PowerShell.Core/CompatiblePSEditions.Module.Tests.ps1
+++ b/test/powershell/Modules/Microsoft.PowerShell.Core/CompatiblePSEditions.Module.Tests.ps1
@@ -324,30 +324,42 @@ Describe "Import-Module from CompatiblePSEditions-checked paths" -Tag "CI" {
 }
 
 Describe "PSModulePath changes interacting with other PowerShell processes" -Tag "Feature" {
-    BeforeAll {
-        if (-not $IsWindows)
-        {
-            return
+    $PSDefaultParameterValues = @{ 'It:Skip' = (-not $IsWindows) }
+
+    Context "System32 module path prepended to PSModulePath" {
+        BeforeAll {
+            if (-not $IsWindows)
+            {
+                return
+            }
+            Add-ModulePath (Join-Path $env:windir "System32\WindowsPowerShell\v1.0\Modules") -Prepend
         }
-        Add-ModulePath (Join-Path $env:windir "System32\WindowsPowerShell\v1.0\Modules") -Prepend
-    }
 
-    AfterAll {
-        if (-not $IsWindows)
-        {
-            return
+        AfterAll {
+            if (-not $IsWindows)
+            {
+                return
+            }
+            Restore-ModulePath
+        }
+
+        It "Allows Windows PowerShell subprocesses to call `$PSHome modules still" {
+            $errors = powershell.exe -Command "Get-ChildItem" 2>&1 | Where-Object { $_ -is [System.Management.Automation.ErrorRecord] }
+            $errors | Should -Be $null
         }
-        Restore-ModulePath
-    }
 
-    It "Allows Windows PowerShell subprocesses to call `$PSHome modules still" -Skip:(-not $IsWindows) {
-        $errors = powershell.exe -Command "Get-ChildItem" 2>&1 | Where-Object { $_ -is [System.Management.Automation.ErrorRecord] }
-        $errors | Should -Be $null
+        It "Allows PowerShell Core 6 subprocesses to call core modules" {
+            $errors = pwsh.exe -Command "Get-ChildItem" 2>&1 | Where-Object { $_ -is [System.Management.Automation.ErrorRecord] }
+            $errors | Should -Be $null
+        }
     }
 
-    It "Allows PowerShell Core 6 subprocesses to call core modules" -Skip:(-not $IsWindows) {
-        $errors = pwsh.exe -Command "Get-ChildItem" 2>&1 | Where-Object { $_ -is [System.Management.Automation.ErrorRecord] }
-        $errors | Should -Be $null
+    It "Does not duplicate the System32 module path in subprocesses" {
+        $sys32ModPathCount = pwsh.exe -C {
+            pwsh.exe -C '$null = $env:PSModulePath -match ([regex]::Escape((Join-Path $env:windir "System32" "WindowsPowerShell" "v1.0" "Modules"))); $matches.Count'
+        }
+
+        $sys32ModPathCount | Should -Be 1
     }
 }