Comment 5 for bug 1660228

Note (for triage):

1) The original file was last edited with inkscape:version="0.47 r22583" (not Inkscape 0.91), and does not use a viewBox to define the document scale. Document width and height are defined (unit-less) as width="1418.974" height="716.26862" (i.e. in user units based on 90dpi).

2) Importing such a legacy file does not trigger the dpi-change dialog (unlike open).

3) Ungrouping the group resulting from 'File > Import' in Inkscape 0.92 may result in unexpected changes wrt stroke widths of the visible paths (actually clones) if the new document uses a different document scale (e.g. based on the default template with user units matching mm). This could be among the root causes for the reported issue(s).
The stroke width is not changed on ungroup when imported into a new document which is based on px (e.g. 'File > New from Template > Generic canvas').

4) I have not been able to reproduce that an unexpected stroke-width property is being added to the original paths which are referenced by (filtered) clones.