diff --git a/reg-tests/http-rules/map_ordering.map b/reg-tests/http-rules/map_ordering.map
index dcd952955..dc9ac71bd 100644
--- a/reg-tests/http-rules/map_ordering.map
+++ b/reg-tests/http-rules/map_ordering.map
@@ -2,3 +2,5 @@
 first.domain.tld first
 domain.tld domain
 second.domain.tld second
+# This entry is used to test duplicate behavior (ie: tree-based match)
+first.domain.tld first_dup
diff --git a/reg-tests/http-rules/map_ordering.vtc b/reg-tests/http-rules/map_ordering.vtc
index 40da465ca..923d19fa5 100644
--- a/reg-tests/http-rules/map_ordering.vtc
+++ b/reg-tests/http-rules/map_ordering.vtc
@@ -1,4 +1,4 @@
-varnishtest "Test list-based matching types ordering"
+varnishtest "Ensure mapfile ordering is preserved when loading the file"
 feature cmd "$HAPROXY_PROGRAM -cc 'version_atleast(2.5-dev0)'"
 feature ignore_unknown_macro
 
@@ -14,9 +14,13 @@ haproxy h1 -conf {
 
     # check list ordering using map_dom (list-based match)
     http-request return hdr dom %[req.hdr(Host),lower,map_dom(${testdir}/map_ordering.map)] if { url_beg /dom }
+
+    # check tree ordering using map_str (tree-based match) and duplicated keys
+    http-request return hdr str %[req.hdr(Host),lower,map_str(${testdir}/map_ordering.map)] if { url_beg /str }
+
 } -start
 
-# Check map ordering
+# Check map ordering for list-based matching types
 client c1 -connect ${h1_fe1_sock} {
     # first.domain.tld is above domain.tld so it should match first
     txreq -url "/dom" -hdr "Host: first.domain.tld"
@@ -30,3 +34,13 @@ client c1 -connect ${h1_fe1_sock} {
     expect resp.status == 200
     expect resp.http.dom == "domain"
 } -run
+
+# Check map ordering for tree-based matching types (check that the matching
+# key is the first one seen in the file)
+client c2 -connect ${h1_fe1_sock} {
+    # first.domain.tld is first mapped to "first" in the mapfile
+    txreq -url "/str" -hdr "Host: first.domain.tld"
+    rxresp
+    expect resp.status == 200
+    expect resp.http.str == "first"
+} -run
diff --git a/src/pattern.c b/src/pattern.c
index 57ef92320..f07223f7c 100644
--- a/src/pattern.c
+++ b/src/pattern.c
@@ -2512,7 +2512,10 @@ int pattern_read_from_file(struct pattern_head *head, unsigned int refflags,
 
 	/* Load reference content in the pattern expression.
 	 * We need to load elements in the same order they were seen in the
-	 * file as list-based matching types may rely on it.
+	 * file. Indeed, some list-based matching types may rely on it as the
+	 * list is positional, and for tree-based matching, even if the tree is
+	 * content-based in case of duplicated keys we only want the first key
+	 * in the file to be considered.
 	 */
 	list_for_each_entry(elt, &ref->head, list) {
 		if (!pat_ref_push(elt, expr, patflags, err)) {