How to define multiple elements in XML Schema with the same name and different attribute value allowed?

Question

I would like to create XML Schema for this chunk of xml, I would like to restrict the values of "name" attribute, so that in output document on and only one instance of day is allowed for each week day:

<a>
  <day name="monday" />
  <day name="tuesday" />
  <day name="wednesday" />
</a>

I have tried to use this:

 <xs:complexType name="a">
  <xs:sequence>
    <xs:element name="day" minOccurs="1" maxOccurs="1">
      <xs:complexType>
        <xs:attribute name="name" use="required">
          <xs:simpleType>
            <xs:restriction base="xs:string">
              <xs:enumeration value="monday" />
            </xs:restriction>
          </xs:simpleType>
        </xs:attribute>
      </xs:complexType>
    </xs:element>
    <xs:element name="day" minOccurs="1" maxOccurs="1">
      <xs:complexType>
        <xs:attribute name="name" use="required">
          <xs:simpleType>
            <xs:restriction base="xs:string">
              <xs:enumeration value="tuesday" />
            </xs:restriction>
          </xs:simpleType>
        </xs:attribute>
      </xs:complexType>
    </xs:element>
  </xs:sequence>
</xs:complexType>

but XML Schema validator in eclipse says error "Multiple elements with name 'day', with different types, appear in the model group.".

Is there any other way?