diff --git a/eng/common/TestResources/New-TestResources.ps1 b/eng/common/TestResources/New-TestResources.ps1
index fa75730dcd2d..508b9b693976 100644
--- a/eng/common/TestResources/New-TestResources.ps1
+++ b/eng/common/TestResources/New-TestResources.ps1
@@ -289,7 +289,8 @@ try {
                 $AzureTestPrincipal
             } else {
                 Log "TestApplicationId was not specified; creating a new service principal in subscription '$SubscriptionId'"
-                $global:AzureTestPrincipal = New-AzADServicePrincipal -Role Owner -Scope "/subscriptions/$SubscriptionId" -DisplayName "test-resources-$($baseName).microsoft.com"
+                $suffix = (New-Guid).ToString('n').Substring(0, 4)
+                $global:AzureTestPrincipal = New-AzADServicePrincipal -Role Owner -Scope "/subscriptions/$SubscriptionId" -DisplayName "test-resources-$($baseName)$suffix.microsoft.com"
                 $global:AzureTestSubscription = $SubscriptionId
 
                 Log "Created service principal '$($AzureTestPrincipal.ApplicationId)'"