diff --git a/changelog.d/15636.misc b/changelog.d/15636.misc
new file mode 100644
index 0000000000..82329c5e43
--- /dev/null
+++ b/changelog.d/15636.misc
@@ -0,0 +1 @@
+Remove duplicate timestamp from test logs (`_trial_temp/test.log`).
diff --git a/tests/test_utils/logging_setup.py b/tests/test_utils/logging_setup.py
index b522163a34..c37f205ed0 100644
--- a/tests/test_utils/logging_setup.py
+++ b/tests/test_utils/logging_setup.py
@@ -40,10 +40,9 @@ def setup_logging() -> None:
     """
     root_logger = logging.getLogger()
 
-    log_format = (
-        "%(asctime)s - %(name)s - %(lineno)d - "
-        "%(levelname)s - %(request)s - %(message)s"
-    )
+    # We exclude `%(asctime)s` from this format because the Twisted logger adds its own
+    # timestamp
+    log_format = "%(name)s - %(lineno)d - " "%(levelname)s - %(request)s - %(message)s"
 
     handler = ToTwistedHandler()
     formatter = logging.Formatter(log_format)