diff --git a/Lib/fontTools/feaLib/builder.py b/Lib/fontTools/feaLib/builder.py
index 1836ebb68..c5c75a7ae 100644
--- a/Lib/fontTools/feaLib/builder.py
+++ b/Lib/fontTools/feaLib/builder.py
@@ -892,9 +892,17 @@ class Builder(object):
             return
         lookup = self.get_lookup_(location, MultipleSubstBuilder)
         if glyph in lookup.mapping:
-            raise FeatureLibError(
-                'Already defined substitution for glyph "%s"' % glyph,
-                location)
+            if replacements == lookup.mapping[glyph]:
+                log.info(
+                    'Removing duplicate multiple substitution from glyph'
+                    ' "%s" to %s%s',
+                    glyph, replacements,
+                    ' at {}:{}:{}'.format(*location) if location else '',
+                )
+            else:
+                raise FeatureLibError(
+                    'Already defined substitution for glyph "%s"' % glyph,
+                    location)
         lookup.mapping[glyph] = replacements
 
     def add_reverse_chain_single_subst(self, location, old_prefix,
diff --git a/Tests/feaLib/builder_test.py b/Tests/feaLib/builder_test.py
index 329b3fdf6..b36a6d5d5 100644
--- a/Tests/feaLib/builder_test.py
+++ b/Tests/feaLib/builder_test.py
@@ -206,9 +206,20 @@ class BuilderTest(unittest.TestCase):
             "feature test {"
             "    sub f_f_i by f f i;"
             "    sub c_t by c t;"
-            "    sub f_f_i by f f i;"
+            "    sub f_f_i by f_f i;"
             "} test;")
 
+    def test_multipleSubst_multipleIdenticalSubstitutionsForSameGlyph_info(self):
+        logger = logging.getLogger("fontTools.feaLib.builder")
+        with CapturingLogHandler(logger, "INFO") as captor:
+            self.build(
+                "feature test {"
+                "    sub f_f_i by f f i;"
+                "    sub c_t by c t;"
+                "    sub f_f_i by f f i;"
+                "} test;")
+        captor.assertRegex(r"Removing duplicate multiple substitution from glyph \"f_f_i\" to \('f', 'f', 'i'\)")
+
     def test_pairPos_redefinition_warning(self):
         # https://github.com/fonttools/fonttools/issues/1147
         logger = logging.getLogger("fontTools.feaLib.builder")