[FIX] l10n_ch: display qr_code once on reprint

Steps to reproduce:
- In Settings/technical/actions/reports: find the invoice report
- in advanced: activate "Reload from attachment"
- create an invoice with a swiss customer
- confirm and print
- print the invoice again

Issue:
There are two pages with the same qr-code

opw-3626815

closes odoo#147281

X-original-commit: a6e0653
Signed-off-by: de Wouters de Bouchout Jean-Benoît (jbw) <jbw@odoo.com>

addons/l10n_ch/models/ir_actions_report.py

@@ -38,6 +38,9 @@ def _render_qweb_pdf_prepare_streams(self, report_ref, data, res_ids=None):
             # Determine which invoices need a QR.
             qr_inv_ids = []
             for invoice in invoices:
+                # avoid duplicating existing streams
+                if report.attachment_use and report.retrieve_attachment(invoice):
+                    continue
                 if invoice.l10n_ch_is_qr_valid:
                     qr_inv_ids.append(invoice.id)
             # Render the additional reports.