As far as I know quantities shown in Schedules take SEOs into consideration when displaying the volumes. However, I do not think there is a separate value that can show you how much volume was added to or subtracted from an element.
All I can think of is you could duplicate the SEO-ed elements, put them on another layer and undo all SEOs on them. This way you would have a version of each such element with and without SEO and you could compared their columes for checking purposes.
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