diff --git a/ChangeLog b/ChangeLog
index f02962e2..fc8ab8c1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -430,7 +430,9 @@ releases.
     - Rewritten without end-anchor ($), because of potential vulnerability on very long URLs.
 * filter.d/apache-badbots.conf - extended to recognize Jorgee Vulnerability Scanner (gh-1882)
 * filter.d/asterisk.conf - fixed failregex AMI Asterisk authentification failed (see gh-1302)
-* filter.d/dovecot.conf - fixed failregex, see gh-1879 (partially cherry-picked from gh-1880)
+* filter.d/dovecot.conf:
+    - fixed failregex, see gh-1879 (partially cherry-picked from gh-1880)
+    - extended to match pam_authenticate failures with "Permission denied" (gh-1897)
 * filter.d/exim.conf - fixed failregex for case of flood attempts with `D=0s` (gh-1887)
 * filter.d/postfix-*.conf - added optional port regex (gh-1902)
 
diff --git a/config/filter.d/dovecot.conf b/config/filter.d/dovecot.conf
index 4df7c752..2019a160 100644
--- a/config/filter.d/dovecot.conf
+++ b/config/filter.d/dovecot.conf
@@ -14,7 +14,7 @@ prefregex = ^%(__prefix_line)s(?:%(_auth_worker)s(?:\([^\)]+\))?: )?(?:%(__pam_a
 
 failregex = ^authentication failure; logname=\S* uid=\S* euid=\S* tty=dovecot ruser=\S* rhost=<HOST>(?:\s+user=\S*)?\s*$
             ^(?:Aborted login|Disconnected)(?::(?: [^ \(]+)+)? \((?:auth failed, \d+ attempts(?: in \d+ secs)?|tried to use (?:disabled|disallowed) \S+ auth)\):(?: user=<[^>]*>,)?(?: method=\S+,)? rip=<HOST>(?:[^>]*(?:, session=<\S+>)?)\s*$
-            ^pam\(\S+,<HOST>\): pam_authenticate\(\) failed: (?:User not known to the underlying authentication module: \d+ Time\(s\)|Authentication failure \(password mismatch\?\))\s*$
+            ^pam\(\S+,<HOST>(?:,\S*)?\): pam_authenticate\(\) failed: (?:User not known to the underlying authentication module: \d+ Time\(s\)|Authentication failure \(password mismatch\?\)|Permission denied)\s*$
             ^[a-z\-]{3,15}\(\S*,<HOST>(?:,\S*)?\): (?:unknown user|invalid credentials)\s*$
             <mdre-<mode>>
 
diff --git a/fail2ban/server/filter.py b/fail2ban/server/filter.py
index be0c8917..2aecd981 100644
--- a/fail2ban/server/filter.py
+++ b/fail2ban/server/filter.py
@@ -459,7 +459,10 @@ class Filter(JailThread):
 			return
 		# Create IP address object
 		ip = IPAddr(ipstr)
-
+		# Avoid exact duplicates
+		if ip in self.__ignoreIpList:
+			logSys.warn("  Ignore duplicate %r (%r), already in ignore list", ip, ipstr)
+			return
 		# log and append to ignore list
 		logSys.debug("  Add %r to ignore list (%r)", ip, ipstr)
 		self.__ignoreIpList.append(ip)
diff --git a/fail2ban/tests/files/logs/dovecot b/fail2ban/tests/files/logs/dovecot
index 34c91d42..9de3d0b4 100644
--- a/fail2ban/tests/files/logs/dovecot
+++ b/fail2ban/tests/files/logs/dovecot
@@ -43,6 +43,9 @@ Jan 29 05:13:50 mail dovecot: auth: passwd-file(username,1.2.3.4): unknown user
 # failJSON: { "time": "2005-01-29T13:54:06", "match": true , "host": "192.0.2.5" }
 Jan 29 13:54:06 auth-worker(22401): Info: sql(admin@example.de,192.0.2.5,<n4JLdHNVngZGpV2j>): unknown user
 
+# failJSON: { "time": "2005-01-29T14:38:51", "match": true , "host": "192.0.2.6", "desc": "PAM Permission denied (gh-1897)" }
+Jan 29 14:38:51 example.com dovecot[24941]: auth-worker(30165): pam(user@example.com,192.0.2.6,<PNHQq8pZhqIKAQGd>): pam_authenticate() failed: Permission denied
+
 # failJSON: { "time": "2005-04-19T05:22:20", "match": true , "host": "80.255.3.104" }
 Apr 19 05:22:20 vm5 auth: pam_unix(dovecot:auth): authentication failure; logname= uid=0 euid=0 tty=dovecot ruser=informix rhost=80.255.3.104
 
diff --git a/fail2ban/tests/servertestcase.py b/fail2ban/tests/servertestcase.py
index 5545afd6..1072c31f 100644
--- a/fail2ban/tests/servertestcase.py
+++ b/fail2ban/tests/servertestcase.py
@@ -441,17 +441,16 @@ class Transmitter(TransmitterBase):
 		self.assertEqual(
 			self.transm.proceed(["set", self.jailName, "addignoreip", value]),
 			(0, [value]))
-		# Will allow duplicate
-		#NOTE: Should duplicates be allowed, or silent ignore like logpath?
+		# Duplicates ignored
 		self.assertEqual(
 			self.transm.proceed(["set", self.jailName, "addignoreip", value]),
-			(0, [value, value]))
+			(0, [value]))
 		self.assertEqual(
 			self.transm.proceed(["get", self.jailName, "ignoreip"]),
-			(0, [value, value]))
+			(0, [value]))
 		self.assertEqual(
 			self.transm.proceed(["set", self.jailName, "delignoreip", value]),
-			(0, [value]))
+			(0, []))
 
 		self.assertEqual(
 			self.transm.proceed(["get", self.jailName, "ignoreself"]),