In fact, the two subreports should be called by the main report almost at the same time. In your scenario, it should be that the execution time of the second subreport is longer than the first subreport which makes the two subreport act as if they kick
off in sequence. If the execution time of the two subreports is more or less the same, they should render in the main report at the same time. You can check that by setting the second subreport to be the same report as the first subreport.
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