fix: don't hijack another Campaign's UTM mirror when display names collide

erpnext/crm/doctype/campaign/campaign.py

@@ -32,19 +32,29 @@ class Campaign(Document):
 		self.sync_utm_campaign()
 
 	def sync_utm_campaign(self):
-		# look up the existing mirror by the stable Campaign link first, so editing
-		# campaign_name updates that mirror instead of creating a duplicate
-		existing = frappe.db.get_value("UTM Campaign", {"crm_campaign": self.name}) or self.campaign_name
-		try:
-			mc = frappe.get_doc("UTM Campaign", existing)
-		except frappe.DoesNotExistError:
-			mc = frappe.new_doc("UTM Campaign")
-			mc.name = self.campaign_name
+		mc = self.get_utm_campaign_mirror()
 		mc.campaign_description = self.description
 		# link by the document name, which differs from campaign_name when a naming series is used
 		mc.crm_campaign = self.name
 		mc.save(ignore_permissions=True)
 
+	def get_utm_campaign_mirror(self):
+		# the mirror already linked to this Campaign, if any (survives campaign_name edits)
+		if owned := frappe.db.get_value("UTM Campaign", {"crm_campaign": self.name}):
+			return frappe.get_doc("UTM Campaign", owned)
+
+		# reuse a same-named mirror only when it isn't already owned by another Campaign,
+		# otherwise two Campaigns sharing a display name would hijack each other's mirror
+		if frappe.db.exists("UTM Campaign", self.campaign_name):
+			same_name = frappe.get_doc("UTM Campaign", self.campaign_name)
+			if not same_name.crm_campaign or same_name.crm_campaign == self.name:
+				return same_name
+
+		# create a fresh mirror, keeping its name unique when the display name is taken
+		mc = frappe.new_doc("UTM Campaign")
+		mc.name = self.name if frappe.db.exists("UTM Campaign", self.campaign_name) else self.campaign_name
+		return mc
+
 	def autoname(self):
 		if frappe.defaults.get_global_default("campaign_naming_by") != "Naming Series":
 			self.name = self.campaign_name

erpnext/crm/doctype/campaign/test_campaign.py

@@ -50,3 +50,21 @@ class TestCampaign(ERPNextTestSuite):
 		# the edit updates the existing mirror rather than creating a second one
 		mirrors = frappe.get_all("UTM Campaign", filters={"crm_campaign": campaign.name})
 		self.assertEqual(len(mirrors), 1)
+
+	def test_two_campaigns_sharing_a_name_do_not_hijack_each_others_mirror(self):
+		# a naming series lets two Campaigns share a display name; each must keep its own mirror
+		original = frappe.defaults.get_global_default("campaign_naming_by")
+		frappe.defaults.set_global_default("campaign_naming_by", "Naming Series")
+		try:
+			first = self.make_campaign(campaign_name="_Test Shared Mirror", naming_series="SAL-CAM-.YYYY.-")
+			second = self.make_campaign(campaign_name="_Test Shared Mirror", naming_series="SAL-CAM-.YYYY.-")
+		finally:
+			frappe.defaults.set_global_default("campaign_naming_by", original or "")
+
+		# the first Campaign's mirror is untouched; the second gets a distinct one
+		self.assertEqual(
+			frappe.db.get_value("UTM Campaign", "_Test Shared Mirror", "crm_campaign"), first.name
+		)
+		second_mirror = frappe.db.get_value("UTM Campaign", {"crm_campaign": second.name})
+		self.assertTrue(second_mirror)
+		self.assertNotEqual(second_mirror, "_Test Shared Mirror")