Hi Pa,
Greetings from Syncfusion. We have analyzed your query, and we would let you know that there is no property to show the same value series, but there is an option to show the series value in the tooltip as you requested. In TooltipBehavior, there is a property called shared, which will show all the series y values to the respective x point. Also, we recommend that you can use the TrackballBehavior feature available in the chart, and by setting tooltipDisplayMode property value as groupAllPoints, you can show all the series values. We have also attached the sample below for your reference.
Screenshot:
Regards,
Yuvaraj.