Multi value date problem

I'm having problems importing the following into one multi value date field:

<products>
  <item>
    <title>Date series A</title>
    <events>
        <event>2012-02-05T07:00:00</event>
        <event>2012-02-06T07:00:00</event>
        <event>2012-02-07T07:00:00</event>
        <event>2012-02-08T07:00:00</event>
    </events>
    <title>Date series B</title>
    <events>
        <event>2012-12-06T07:00:00</event>
        <event>2012-12-09T07:00:00</event>
    </events>
  </item>
</products>

Only the first date value is imported into each node's event field.

The date field mapping seem to use a special syntax, for example "field_event:start:" and "field_event:end:"

My mappings:

context is mapped with "//item"
"field_event:start:" is mapped with "events//date"
"field_event:end:" is mapped with "events//date"

Using an the event field for the content type with cck type text rather than cck type date works fine for importing multiple values.