sequence with elements with the same name is not allowed?

Hello,

is the following XML Schema valid?

<?xml version="1.0" encoding="ISO-8859-1"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
 <xsd:complexType name="TControl">
  <xsd:sequence>
   <xsd:element name="Properties">
    <xsd:complexType>
     <xsd:sequence>
      <xsd:element name="Visible" type="xsd:boolean"/>
      <xsd:element name="Enabled" type="xsd:boolean"/>
     </xsd:sequence>
    </xsd:complexType>
   </xsd:element>
   <xsd:element name="Text"/>
   <xsd:element name="Properties">
    <xsd:complexType>
     <xsd:sequence>
      <xsd:element name="Readonly" type="xsd:boolean"/>
     </xsd:sequence>
    </xsd:complexType>
   </xsd:element>
  </xsd:sequence>
 </xsd:complexType>
 <xsd:element name="root" type="TControl"/>
</xsd:schema>

Most of my programs show an error like "Duplicate element decl in the same 
scope: Properties", but I can't find such a restriction in the spec.

Hans-Peter Kuechler