Question

Now I use something like this:

<Component Id="RegistryEntries" Guid="<guid>" KeyPath="yes">  
  <RegistryKey Root="HKCU" Key="<path>" Action="createAndRemoveOnUninstall">  
    <RegistryValue Name="myStrings" Action="append" Type="multiString">  
      1  
    </RegistryValue>  
    <RegistryValue Name="myStrings" Action="append" Type="multiString">  
      2
    </RegistryValue>  
    <RegistryValue Name="myStrings" Action="append" Type="multiString">  
      3
    </RegistryValue>  
    <RegistryValue Name="myString" Value="x" Type="string"/>  
  </RegistryKey>  
</Component>  

But I have the next error:

The primary key "reg<key>" is duplicated in table ‘Registry’. Please remove one of the entries or rename a part of the primary key to avoid the collision.

ANSWER: After Yan’s answer my xml looks like:

<Component Id="RegistryEntries" Guid="<guid>">
  <RegistryKey Root="HKCU" Key="<path>" Action="createAndRemoveOnUninstall">
    <RegistryValue Name="myStrings" Action="append" Type="multiString">
      <MultiStringValue Name="myStrings" Action="append" Type="multiString">  
        1
      </MultiStringValue>
      <MultiStringValue Name="myStrings" Action="append" Type="multiString">  
        2
      </MultiStringValue>
      <MultiStringValue Name="myStrings" Action="append" Type="multiString">  
        3
      </MultiStringValue>
    </RegistryValue>
    <RegistryValue Name="myString" Value="x" Type="string"/>
  </RegistryKey>
</Component>

Answer 1

Use MultiStringValue element.