diff -r de0fa478c22e Misc/NEWS
--- a/Misc/NEWS	Wed Oct 05 03:24:45 2016 +1100
+++ b/Misc/NEWS	Wed Oct 05 13:40:56 2016 +0900
@@ -7,12 +7,15 @@
 
 *Release date: XXXX-XX-XX*
 
 Core and Builtins
 -----------------
 
+- Issue #28201: Dict reduces possibility of 2nd conflict in hash table when
+  hashes have same lower bits.
+
 - Issue #28350: String constants with null character no longer interned.
 
 - Issue #26617: Fix crash when GC runs during weakref callbacks.
 
 - Issue #27942: String constants now interned recursively in tuples and frozensets.
 
diff -r de0fa478c22e Objects/dictobject.c
--- a/Objects/dictobject.c	Wed Oct 05 03:24:45 2016 +1100
+++ b/Objects/dictobject.c	Wed Oct 05 13:40:56 2016 +0900
@@ -627,26 +627,26 @@
 }
 
 /* Search index of hash table from offset of entry table */
 static Py_ssize_t
 lookdict_index(PyDictKeysObject *k, Py_hash_t hash, Py_ssize_t index)
 {
-    size_t i, perturb;
+    size_t i;
     size_t mask = DK_MASK(k);
     Py_ssize_t ix;
 
     i = (size_t)hash & mask;
     ix = dk_get_index(k, i);
     if (ix == index) {
         return i;
     }
     if (ix == DKIX_EMPTY) {
         return DKIX_EMPTY;
     }
 
-    for (perturb = hash; ; perturb >>= PERTURB_SHIFT) {
+    for (size_t perturb = hash >> PERTURB_SHIFT; ; perturb >>= PERTURB_SHIFT) {
         i = mask & ((i << 2) + i + perturb + 1);
         ix = dk_get_index(k, i);
         if (ix == index) {
             return i;
         }
         if (ix == DKIX_EMPTY) {
@@ -682,13 +682,13 @@
 where the key index should be inserted.
 */
 static Py_ssize_t
 lookdict(PyDictObject *mp, PyObject *key,
          Py_hash_t hash, PyObject ***value_addr, Py_ssize_t *hashpos)
 {
-    size_t i, perturb, mask;
+    size_t i, mask;
     Py_ssize_t ix, freeslot;
     int cmp;
     PyDictKeysObject *dk;
     PyDictKeyEntry *ep0, *ep;
     PyObject *startkey;
 
@@ -737,13 +737,13 @@
                 goto top;
             }
         }
         freeslot = -1;
     }
 
-    for (perturb = hash; ; perturb >>= PERTURB_SHIFT) {
+    for (size_t perturb = hash >> PERTURB_SHIFT; ; perturb >>= PERTURB_SHIFT) {
         i = ((i << 2) + i + perturb + 1) & mask;
         ix = dk_get_index(dk, i);
         if (ix == DKIX_EMPTY) {
             if (hashpos != NULL) {
                 *hashpos = (freeslot == -1) ? (Py_ssize_t)i : freeslot;
             }
@@ -794,13 +794,13 @@
 
 /* Specialized version for string-only keys */
 static Py_ssize_t
 lookdict_unicode(PyDictObject *mp, PyObject *key,
                  Py_hash_t hash, PyObject ***value_addr, Py_ssize_t *hashpos)
 {
-    size_t i, perturb;
+    size_t i;
     size_t mask = DK_MASK(mp->ma_keys);
     Py_ssize_t ix, freeslot;
     PyDictKeyEntry *ep, *ep0 = DK_ENTRIES(mp->ma_keys);
 
     assert(mp->ma_values == NULL);
     /* Make sure this function doesn't have to handle non-unicode keys,
@@ -832,13 +832,13 @@
             *value_addr = &ep->me_value;
             return ix;
         }
         freeslot = -1;
     }
 
-    for (perturb = hash; ; perturb >>= PERTURB_SHIFT) {
+    for (size_t perturb = hash >> PERTURB_SHIFT; ; perturb >>= PERTURB_SHIFT) {
         i = mask & ((i << 2) + i + perturb + 1);
         ix = dk_get_index(mp->ma_keys, i);
         if (ix == DKIX_EMPTY) {
             if (hashpos != NULL) {
                 *hashpos = (freeslot == -1) ? (Py_ssize_t)i : freeslot;
             }
@@ -869,13 +869,13 @@
  * will be present. */
 static Py_ssize_t
 lookdict_unicode_nodummy(PyDictObject *mp, PyObject *key,
                          Py_hash_t hash, PyObject ***value_addr,
                          Py_ssize_t *hashpos)
 {
-    size_t i, perturb;
+    size_t i;
     size_t mask = DK_MASK(mp->ma_keys);
     Py_ssize_t ix;
     PyDictKeyEntry *ep, *ep0 = DK_ENTRIES(mp->ma_keys);
 
     assert(mp->ma_values == NULL);
     /* Make sure this function doesn't have to handle non-unicode keys,
@@ -902,13 +902,13 @@
         (ep->me_hash == hash && unicode_eq(ep->me_key, key))) {
         if (hashpos != NULL)
             *hashpos = i;
         *value_addr = &ep->me_value;
         return ix;
     }
-    for (perturb = hash; ; perturb >>= PERTURB_SHIFT) {
+    for (size_t perturb = hash >> PERTURB_SHIFT; ; perturb >>= PERTURB_SHIFT) {
         i = mask & ((i << 2) + i + perturb + 1);
         ix = dk_get_index(mp->ma_keys, i);
         assert (ix != DKIX_DUMMY);
         if (ix == DKIX_EMPTY) {
             if (hashpos != NULL)
                 *hashpos = i;
@@ -935,13 +935,13 @@
  * so algorithm is the same as lookdict_unicode_nodummy.
  */
 static Py_ssize_t
 lookdict_split(PyDictObject *mp, PyObject *key,
                Py_hash_t hash, PyObject ***value_addr, Py_ssize_t *hashpos)
 {
-    size_t i, perturb;
+    size_t i;
     size_t mask = DK_MASK(mp->ma_keys);
     Py_ssize_t ix;
     PyDictKeyEntry *ep, *ep0 = DK_ENTRIES(mp->ma_keys);
 
     /* mp must split table */
     assert(mp->ma_values != NULL);
@@ -968,13 +968,13 @@
         (ep->me_hash == hash && unicode_eq(ep->me_key, key))) {
         if (hashpos != NULL)
             *hashpos = i;
         *value_addr = &mp->ma_values[ix];
         return ix;
     }
-    for (perturb = hash; ; perturb >>= PERTURB_SHIFT) {
+    for (size_t perturb = hash >> PERTURB_SHIFT; ; perturb >>= PERTURB_SHIFT) {
         i = mask & ((i << 2) + i + perturb + 1);
         ix = dk_get_index(mp->ma_keys, i);
         if (ix == DKIX_EMPTY) {
             if (hashpos != NULL)
                 *hashpos = i;
             *value_addr = NULL;
@@ -1061,26 +1061,27 @@
 
    The dict must be combined. */
 static void
 find_empty_slot(PyDictObject *mp, PyObject *key, Py_hash_t hash,
                 PyObject ***value_addr, Py_ssize_t *hashpos)
 {
-    size_t i, perturb;
+    size_t i;
     size_t mask = DK_MASK(mp->ma_keys);
     Py_ssize_t ix;
     PyDictKeyEntry *ep, *ep0 = DK_ENTRIES(mp->ma_keys);
 
     assert(!_PyDict_HasSplitTable(mp));
     assert(hashpos != NULL);
     assert(key != NULL);
 
     if (!PyUnicode_CheckExact(key))
         mp->ma_keys->dk_lookup = lookdict;
     i = hash & mask;
     ix = dk_get_index(mp->ma_keys, i);
-    for (perturb = hash; ix != DKIX_EMPTY; perturb >>= PERTURB_SHIFT) {
+    for (size_t perturb = hash >> PERTURB_SHIFT; ix != DKIX_EMPTY;
+         perturb >>= PERTURB_SHIFT) {
         i = (i << 2) + i + perturb + 1;
         ix = dk_get_index(mp->ma_keys, i & mask);
     }
     ep = &ep0[mp->ma_keys->dk_nentries];
     *hashpos = i & mask;
     assert(ep->me_value == NULL);
@@ -1199,25 +1200,25 @@
 must set them correctly
 */
 static void
 insertdict_clean(PyDictObject *mp, PyObject *key, Py_hash_t hash,
                  PyObject *value)
 {
-    size_t i, perturb;
+    size_t i;
     PyDictKeysObject *k = mp->ma_keys;
     size_t mask = (size_t)DK_SIZE(k)-1;
     PyDictKeyEntry *ep0 = DK_ENTRIES(mp->ma_keys);
     PyDictKeyEntry *ep;
 
     assert(k->dk_lookup != NULL);
     assert(value != NULL);
     assert(key != NULL);
     assert(PyUnicode_CheckExact(key) || k->dk_lookup == lookdict);
     i = hash & mask;
-    for (perturb = hash; dk_get_index(k, i) != DKIX_EMPTY;
-         perturb >>= PERTURB_SHIFT) {
+    for (size_t perturb = hash >> PERTURB_SHIFT;
+         dk_get_index(k, i) != DKIX_EMPTY; perturb >>= PERTURB_SHIFT) {
         i = mask & ((i << 2) + i + perturb + 1);
     }
     ep = &ep0[k->dk_nentries];
     assert(ep->me_value == NULL);
     dk_set_index(k, i, k->dk_nentries);
     k->dk_nentries++;