diff --git a/erpnext/crm/doctype/timezone/timezone.py b/erpnext/crm/doctype/timezone/timezone.py
index f0da6e3..2c77023 100644
--- a/erpnext/crm/doctype/timezone/timezone.py
+++ b/erpnext/crm/doctype/timezone/timezone.py
@@ -12,3 +12,6 @@
         if self.offset > 720 or self.offset < -720:
             frappe.throw(
                 'Timezone offsets must be between -720 and +720 minutes')
+        if frappe.db.exists({'doctype':'Timezone','offset':self.offset}):
+            frappe.throw(
+                'Timezone offsets need to be unique')
\ No newline at end of file