How can I track VAST events with multiple pixels?

I have a linear preroll add like below. I'd like to track each event (like "start", "skip" etc.) with multiple pixels. Specifically: one for my purposes and one provided by the client. How do I accomplish that?

I did try inserting multiple <Tracking event="start"> tags with no result. I also tried comma separated: <Tracking event="start"><![CDATA[http://x.pl/start1.jpg,http://x.pl/start3.jpg]]></Tracking>

The only solution that does work is using progress event with matching time offsets. But this is a poor solution (especially that it cannot mock skip event)

We use video.js@6.8 + videojs-ima.

The code:

<?xml version="1.0" encoding="utf-8"?>
<VAST version="4.0">
    <Ad id="7897490" conditionalAd="false" sequence="1">
        <InLine>
            <!-- .... -->
            <Creatives>
                <Creative id="21719385">
                    <Linear>
                        <!-- .... -->
                        <TrackingEvents>
                            <Tracking event="skip"><![CDATA[http://example.com/skip.jpg]]></Tracking>
                            <Tracking event="start"><![CDATA[http://example.com/start1.jpg]]></Tracking>
                            <Tracking event="progress" offset="00:00:01.000"><![CDATA[http://example.com/start2.jpg]]></Tracking>
                            <Tracking event="firstQuartile"><![CDATA[http://example.com/firstQuartile.jpg]]></Tracking>
                            <Tracking event="midpoint"><![CDATA[http://example.com/midpoint.jpg]]></Tracking>
                            <Tracking event="thirdQuartile"><![CDATA[http://example.com/thirdQuartile.jpg]]></Tracking>
                            <Tracking event="complete"><![CDATA[http://example.com/complete.jpg]]></Tracking>

                        </TrackingEvents>
                        <!-- .... -->
                        <MediaFiles>
                                <!-- .... -->
                        </MediaFiles>
                    </Linear>
                </Creative>
            </Creatives>
        </InLine>
    </Ad>
</VAST>

Any insights appreciated!

Additional tracking pixels should have their own node. So instead of

<Tracking event="start"><![CDATA[http://x.pl/start1.jpg,http://x.pl/start3.jpg]]></Tracking>

Just use

<Tracking event="start"><![CDATA[http://x.pl/start1.jpg]]></Tracking>
<Tracking event="start"><![CDATA[http://x.pl/start3.jpg]]></Tracking>