diff --git a/web_pwa_customize/models/res_config_settings.py b/web_pwa_customize/models/res_config_settings.py
index 2f4226dcbd5c..c8e77cc60618 100644
--- a/web_pwa_customize/models/res_config_settings.py
+++ b/web_pwa_customize/models/res_config_settings.py
@@ -32,7 +32,7 @@ def get_values(self):
         pwa_icon_attachment = (
             self.env["ir.attachment"]
             .sudo()
-            .search([("url", "like", self._pwa_icon_url_base + ".")])
+            .search([("url", "like", self._pwa_icon_url_base + ".")], limit=1)
         )
         res["pwa_icon"] = pwa_icon_attachment.datas if pwa_icon_attachment else False
         return res
diff --git a/web_pwa_customize/tests/test_web_pwa_customize.py b/web_pwa_customize/tests/test_web_pwa_customize.py
index 5d6935a2119b..af503cdaa78d 100644
--- a/web_pwa_customize/tests/test_web_pwa_customize.py
+++ b/web_pwa_customize/tests/test_web_pwa_customize.py
@@ -1,7 +1,7 @@
 # Copyright 2024 Tecnativa - Víctor Martínez
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
-from odoo.tests.common import tagged
+from odoo.tests.common import Form, tagged
 
 from odoo.addons.base.tests.common import HttpCaseWithUserDemo
 
@@ -24,3 +24,41 @@ def test_webmanifest_customize(self):
         self.assertEqual(data["short_name"], "SHORT-NAME")
         self.assertEqual(data["background_color"], "#2E69B5")
         self.assertEqual(data["theme_color"], "#2E69B4")
+
+    def test_default_get_pwa_icon_singleton(self):
+        """Test default_get doesn't crash with multiple PWA icon attachments.
+
+        Reproduces the real scenario: duplicate attachments with the same URL
+        accumulate due to race conditions or repeated saves. The search in
+        get_values() matches all of them, and .datas triggers ensure_one().
+        """
+        attachment_model = self.env["ir.attachment"].sudo()
+        # Simulate production scenario: 2 attachments with the same URL
+        # (the actual bug — duplicate base icon)
+        for _ in range(2):
+            attachment_model.create(
+                {
+                    "name": "/web_pwa_customize/icon.svg",
+                    "url": "/web_pwa_customize/icon.svg",
+                    "type": "binary",
+                    "datas": "dGVzdA==",
+                    "mimetype": "image/svg+xml",
+                }
+            )
+        # Also create resized PNG variants (normal scenario)
+        for size in ["128x128", "144x144", "152x152"]:
+            attachment_model.create(
+                {
+                    "name": f"/web_pwa_customize/icon{size}.png",
+                    "url": f"/web_pwa_customize/icon{size}.png",
+                    "type": "binary",
+                    "datas": "dGVzdA==",
+                    "mimetype": "image/png",
+                }
+            )
+        # Form() triggers default_get() which calls get_values() via super chain
+        # This is the exact flow that crashes in production
+        settings_form = Form(self.env["res.config.settings"])
+        # If the bug exists, this line raises:
+        # ValueError: Expected singleton: ir.attachment(137, 123)
+        settings_form.save()