Build 4.5.0.88 of xlsgen improves how linking behaves in duplicate scenarios involving external workbooks.
Before this build, any link from an external workbook, for instance a chart series formula, would be expanded to literals and copied over to the destination sheet. Beginning with this build, links are brought as is, as long as the links depend only on the sheet being duplicated. When the link depends on a sheet not being copied over, the link is expanded as literals and brought over as literals.
This build also exposes the text boxes collection inside charts. So far only pictures and vector shapes were exposed (for querying purposes).