diff --git a/pkg/crd/markers/validation.go b/pkg/crd/markers/validation.go
index c91f5e6a1..3e7e08a7e 100644
--- a/pkg/crd/markers/validation.go
+++ b/pkg/crd/markers/validation.go
@@ -666,6 +666,14 @@ func (m XValidation) ApplyToSchema(schema *apiext.JSONSchemaProps) error {
 		}
 	}
 
+	// Check if this validation rule already exists to prevent duplication
+	for _, existingRule := range schema.XValidations {
+		if existingRule.Rule == m.Rule {
+			// Rule already exists, don't add it again
+			return nil
+		}
+	}
+
 	schema.XValidations = append(schema.XValidations, apiext.ValidationRule{
 		Rule:              m.Rule,
 		Message:           m.Message,
diff --git a/pkg/crd/testdata/oneof/types.go b/pkg/crd/testdata/oneof/types.go
index 430cc3a2d..0ca18f73b 100644
--- a/pkg/crd/testdata/oneof/types.go
+++ b/pkg/crd/testdata/oneof/types.go
@@ -36,6 +36,9 @@ type OneofSpec struct {
 	TypeWithMultipleAtLeastOneofs *TypeWithMultipleAtLeastOneofs `json:"typeWithMultipleAtLeastOneOf,omitempty"`
 
 	TypeWithAllOneOf *TypeWithAllOneofs `json:"typeWithAllOneOf,omitempty"`
+
+	// The validation rule on TypeWithOneofs should not be duplicated.
+	SameTypeWithOneof *TypeWithOneofs `json:"sameTypeWithOneof,omitempty"`
 }
 
 // +kubebuilder:validation:XValidation:message="only one of foo|bar may be set",rule="!(has(self.foo) && has(self.bar))"
diff --git a/pkg/crd/testdata/testdata.kubebuilder.io_oneofs.yaml b/pkg/crd/testdata/testdata.kubebuilder.io_oneofs.yaml
index 3ae323948..8f11d1fb4 100644
--- a/pkg/crd/testdata/testdata.kubebuilder.io_oneofs.yaml
+++ b/pkg/crd/testdata/testdata.kubebuilder.io_oneofs.yaml
@@ -60,6 +60,20 @@ spec:
                 - message: at most one of the fields in [foo bar] may be set
                   rule: '[has(self.foo),has(self.bar)].filter(x,x==true).size() <=
                     1'
+              sameTypeWithOneof:
+                description: The validation rule on TypeWithOneofs should not be duplicated.
+                properties:
+                  bar:
+                    type: string
+                  foo:
+                    type: string
+                type: object
+                x-kubernetes-validations:
+                - message: only one of foo|bar may be set
+                  rule: '!(has(self.foo) && has(self.bar))'
+                - message: at most one of the fields in [foo bar] may be set
+                  rule: '[has(self.foo),has(self.bar)].filter(x,x==true).size() <=
+                    1'
               secondTypeWithExactOneof:
                 properties:
                   a: