diff --git a/src/test/regress/bin/diff b/src/test/regress/bin/diff
index 0bbbe92ae..66a558c45 100755
--- a/src/test/regress/bin/diff
+++ b/src/test/regress/bin/diff
@@ -30,8 +30,15 @@ fi
 if test -z "${VANILLATEST:-}"
 then
 	touch "$file1"  # when adding a new test the expected file does not exist
-	sed -Ef "$BASEDIR/normalize.sed" < "$file1" > "$file1.modified"
-	sed -Ef "$BASEDIR/normalize.sed" < "$file2" > "$file2.modified"
+	normalize_file="$BASEDIR/normalize.sed"
+	# when running tests on an existing cluster some changes need to be done on
+	# normalize.sed file. So a new file is used.
+	if [[ -f "$BASEDIR/normalize_modified.sed" ]]
+	then
+		normalize_file="$BASEDIR/normalize_modified.sed"
+	fi
+	sed -Ef "$normalize_file" < "$file1" > "$file1.modified"
+	sed -Ef "$normalize_file" < "$file2" > "$file2.modified"
 	"$DIFF" -w $args "$file1.modified" "$file2.modified" | LC_CTYPE=C.UTF-8 diff-filter "$BASEDIR/normalize.sed"
 	exit ${PIPESTATUS[0]}
 else
diff --git a/src/test/regress/pg_regress_multi.pl b/src/test/regress/pg_regress_multi.pl
index ce57dcd2b..8636e6b95 100755
--- a/src/test/regress/pg_regress_multi.pl
+++ b/src/test/regress/pg_regress_multi.pl
@@ -300,6 +300,28 @@ if ( $conninfo )
         $dbname = $convals{dbname};
     }
 
+    open my $in, '<', "bin/normalize.sed" or die "Cannot open normalize.sed file\n";
+    open my $out, '>', "bin/normalize_modified.sed" or die "Cannot open normalize_modified.sed file\n";
+
+    while ( <$in> )
+    {
+        print $out $_;
+    }
+
+    close $in;
+
+
+    print $out "\n";
+    print $out "s/\\bdbname=regression\\b/dbname=<db>/g\n";
+    print $out "s/\\bdbname=$dbname\\b/dbname=<db>/g\n";
+    print $out "s/\\b$user\\b/<user>/g\n";
+    print $out "s/\\bpostgres\\b/<user>/g\n";
+    print $out "s/\\blocalhost\\b/<host>/g\n";
+    print $out "s/\\b$host\\b/<host>/g\n";
+    print $out "s/\\b576[0-9][0-9]\\b/xxxxx/g\n";
+    print $out "s/", substr("$masterPort", 0, length("$masterPort")-2), "[0-9][0-9]/xxxxx/g\n";
+
+
     my $worker1port = `psql "$conninfo" -t -c "SELECT nodeport FROM pg_dist_node ORDER BY nodeid LIMIT 1;"`;
     my $worker2port = `psql "$conninfo" -t -c "SELECT nodeport FROM pg_dist_node ORDER BY nodeid OFFSET 1 LIMIT 1;"`;