Internal PDF import: Incorrect clipping if object has two consecutive clippings

Summary:

PDFs containing certain Onenote pencils are incorrectly imported. Separated out from inbox#3189

Steps to reproduce:

• open Inkscape
• open https://gitlab.com/inkscape/inbox/uploads/590f58258cb852ebcff8cef3d35f659e/Test.pdf or https://gitlab.com/inkscape/inbox/uploads/7188fb58396e1103bf2561d4096ca0d8/COB.pdf from inbox#3189 using internal import

What happened?

What should have happened?

Sample attachments:

Version info

Inkscape 1.3-dev (7e1a6f8, 2023-02-24)

    GLib version:     2.64.6
    GTK version:      3.24.20
    glibmm version:   2.64.2
    gtkmm version:    3.24.2
    libxml2 version:  2.9.10
    libxslt version:  1.1.34
    Cairo version:    1.17.7
    Pango version:    1.44.7
    HarfBuzz version: 2.6.4

    OS version:       Ubuntu 22.04.2 LTS