diff --git a/sys/netpfil/pf/pf.c b/sys/netpfil/pf/pf.c
--- a/sys/netpfil/pf/pf.c
+++ b/sys/netpfil/pf/pf.c
@@ -7795,6 +7795,9 @@
 		dndir = pd->dir;
 	}
 
+	if (pd->pf_mtag->flags & PF_MTAG_FLAG_DUMMYNETED)
+		return (false);
+
 	memset(dnflow, 0, sizeof(*dnflow));
 
 	if (pd->dport != NULL)
@@ -7936,6 +7939,7 @@
 
 		if (pf_pdesc_to_dnflow(pd, r, s, &dnflow)) {
 			pd->pf_mtag->flags |= PF_MTAG_FLAG_DUMMYNET;
+			pd->pf_mtag->flags |= PF_MTAG_FLAG_DUMMYNETED;
 			ip_dn_io_ptr(m0, &dnflow);
 			if (*m0 != NULL) {
 				pd->pf_mtag->flags &= ~PF_MTAG_FLAG_ROUTE_TO;
diff --git a/sys/netpfil/pf/pf_mtag.h b/sys/netpfil/pf/pf_mtag.h
--- a/sys/netpfil/pf/pf_mtag.h
+++ b/sys/netpfil/pf/pf_mtag.h
@@ -41,7 +41,7 @@
 #define	PF_MTAG_FLAG_TRANSLATE_LOCALHOST	0x04
 #define	PF_MTAG_FLAG_PACKET_LOOPED		0x08
 #define	PF_MTAG_FLAG_FASTFWD_OURS_PRESENT	0x10
-/*						0x20 unused */
+#define	PF_MTAG_FLAG_DUMMYNETED			0x20
 #define	PF_MTAG_FLAG_DUPLICATED			0x40
 #define	PF_MTAG_FLAG_SYNCOOKIE_RECREATED	0x80
 
diff --git a/tests/sys/netpfil/pf/route_to.sh b/tests/sys/netpfil/pf/route_to.sh
--- a/tests/sys/netpfil/pf/route_to.sh
+++ b/tests/sys/netpfil/pf/route_to.sh
@@ -615,6 +615,58 @@
 	pft_cleanup
 }
 
+atf_test_case "dummynet_double" "cleanup"
+dummynet_double_head()
+{
+	atf_set descr 'Ensure dummynet is not applied multiple times'
+	atf_set require.user root
+}
+
+dummynet_double_body()
+{
+	pft_init
+	dummynet_init
+
+	epair_one=$(vnet_mkepair)
+	epair_two=$(vnet_mkepair)
+
+	ifconfig ${epair_one}a 192.0.2.1/24 up
+
+	vnet_mkjail alcatraz ${epair_one}b ${epair_two}a
+	jexec alcatraz ifconfig ${epair_one}b 192.0.2.2/24 up
+	jexec alcatraz ifconfig ${epair_two}a 198.51.100.1/24 up
+	jexec alcatraz sysctl net.inet.ip.forwarding=1
+
+	vnet_mkjail singsing ${epair_two}b
+	jexec singsing ifconfig ${epair_two}b 198.51.100.2/24 up
+	jexec singsing route add default 198.51.100.1
+
+	route add 198.51.100.0/24 192.0.2.2
+
+	jexec alcatraz dnctl pipe 1 config delay 800
+
+	jexec alcatraz pfctl -e
+	pft_set_rules alcatraz \
+		"set reassemble yes" \
+		"nat on ${epair_two}a from 192.0.2.0/24 -> (${epair_two}a)" \
+		"pass in route-to (${epair_two}a 198.51.100.2) inet proto icmp all icmp-type echoreq dnpipe (1, 1)" \
+		"pass out route-to (${epair_two}a 198.51.100.2) inet proto icmp all icmp-type echoreq"
+
+	ping -c 1 198.51.100.2
+	jexec alcatraz pfctl -sr -vv
+	jexec alcatraz pfctl -ss -vv
+
+	# We expect to be delayed 1.6 seconds, so timeout of two seconds passes, but
+	# timeout of 1 does not.
+	atf_check -s exit:0 -o ignore ping -t 2 -c 1 198.51.100.2
+	atf_check -s exit:2 -o ignore ping -t 1 -c 1 198.51.100.2
+}
+
+dummynet_double_cleanup()
+{
+	pft_cleanup
+}
+
 atf_init_test_cases()
 {
 	atf_add_test_case "v4"
@@ -628,4 +680,5 @@
 	atf_add_test_case "ifbound_reply_to"
 	atf_add_test_case "ifbound_reply_to_v6"
 	atf_add_test_case "dummynet_frag"
+	atf_add_test_case "dummynet_double"
 }