diff --git a/jsonschema/_utils.py b/jsonschema/_utils.py
index e5051ec10..0cfb84fdf 100644
--- a/jsonschema/_utils.py
+++ b/jsonschema/_utils.py
@@ -188,7 +188,8 @@ def uniq(container):
         sliced = itertools.islice(sort, 1, None)
 
         for i, j in zip(sort, sliced):
-            return not _sequence_equal(i, j)
+            if _sequence_equal(i, j):
+                return False
 
     except (NotImplementedError, TypeError):
         seen = []
diff --git a/jsonschema/tests/test_jsonschema_test_suite.py b/jsonschema/tests/test_jsonschema_test_suite.py
index 695009dcd..da46cf381 100644
--- a/jsonschema/tests/test_jsonschema_test_suite.py
+++ b/jsonschema/tests/test_jsonschema_test_suite.py
@@ -164,16 +164,6 @@ def leap_second(test):
         narrow_unicode_build(test)
         or missing_format(draft3_format_checker)(test)
         or complex_email_validation(test)
-        or skip(
-            message=bug(866),
-            subject="uniqueItems",
-            description="non-unique array of more than two arrays is invalid",
-        )(test)
-        or skip(
-            message=bug(866),
-            subject="uniqueItems",
-            description="non-unique array of strings is invalid",
-        )(test)
         or skip(
             message=bug(371),
             subject="ref",
@@ -200,16 +190,6 @@ def leap_second(test):
         or leap_second(test)
         or missing_format(draft4_format_checker)(test)
         or complex_email_validation(test)
-        or skip(
-            message=bug(866),
-            subject="uniqueItems",
-            description="non-unique array of more than two arrays is invalid",
-        )(test)
-        or skip(
-            message=bug(866),
-            subject="uniqueItems",
-            description="non-unique array of strings is invalid",
-        )(test)
         or skip(
             message=bug(),
             subject="ref",
@@ -271,16 +251,6 @@ def leap_second(test):
         or leap_second(test)
         or missing_format(draft6_format_checker)(test)
         or complex_email_validation(test)
-        or skip(
-            message=bug(866),
-            subject="uniqueItems",
-            description="non-unique array of more than two arrays is invalid",
-        )(test)
-        or skip(
-            message=bug(866),
-            subject="uniqueItems",
-            description="non-unique array of strings is invalid",
-        )(test)
         or skip(
             message=bug(371),
             subject="ref",
@@ -320,16 +290,6 @@ def leap_second(test):
         or leap_second(test)
         or missing_format(draft7_format_checker)(test)
         or complex_email_validation(test)
-        or skip(
-            message=bug(866),
-            subject="uniqueItems",
-            description="non-unique array of more than two arrays is invalid",
-        )(test)
-        or skip(
-            message=bug(866),
-            subject="uniqueItems",
-            description="non-unique array of strings is invalid",
-        )(test)
         or skip(
             message=bug(371),
             subject="ref",
@@ -396,16 +356,6 @@ def leap_second(test):
             message="unevaluatedItems is different in 2019-09 (needs work).",
             subject="unevaluatedItems",
         )(test)
-        or skip(
-            message=bug(866),
-            subject="uniqueItems",
-            description="non-unique array of more than two arrays is invalid",
-        )(test)
-        or skip(
-            message=bug(866),
-            subject="uniqueItems",
-            description="non-unique array of strings is invalid",
-        )(test)
         or skip(
             message="dynamicRef support isn't working yet.",
             subject="recursiveRef",
@@ -450,16 +400,6 @@ def leap_second(test):
     Validator=Draft202012Validator,
     skip=lambda test: (
         narrow_unicode_build(test)
-        or skip(
-            message=bug(866),
-            subject="uniqueItems",
-            description="non-unique array of more than two arrays is invalid",
-        )(test)
-        or skip(
-            message=bug(866),
-            subject="uniqueItems",
-            description="non-unique array of strings is invalid",
-        )(test)
         or skip(
             message="dynamicRef support isn't working yet.",
             subject="dynamicRef",