diff --git a/src/Attr.cc b/src/Attr.cc
index 8f6b54a13c..a5046dd764 100644
--- a/src/Attr.cc
+++ b/src/Attr.cc
@@ -195,6 +195,12 @@ Attributes::Attributes(std::vector<AttrPtr> a,
 
 void Attributes::AddAttr(AttrPtr attr)
 	{
+	// Display a warning for duplicated tags on a type. &log tags are intentionally
+	// ignored here because duplicate log tags on record types are valid, and don't
+	// cause any significant breakage for other types.
+	if ( attr->Tag() != ATTR_LOG && Find(attr->Tag()) )
+		reporter->Warning("Found duplicate tag %s", attr_name(attr->Tag()));
+
 	// We overwrite old attributes by deleting them first.
 	RemoveAttr(attr->Tag());
 	attrs_list.push_back(attr.get());
diff --git a/testing/btest/Baseline/language.attr-default-global-set-error/out b/testing/btest/Baseline/language.attr-default-global-set-error/out
index ddcc6a8345..27ebbf3356 100644
--- a/testing/btest/Baseline/language.attr-default-global-set-error/out
+++ b/testing/btest/Baseline/language.attr-default-global-set-error/out
@@ -1,5 +1,6 @@
-error in /home/jon/pro/zeek/zeek/testing/btest/.tmp/language.attr-default-global-set-error/attr-default-global-set-error.zeek, line 4: &default is not valid for global variables except for tables (&default=0)
-error in /home/jon/pro/zeek/zeek/testing/btest/.tmp/language.attr-default-global-set-error/attr-default-global-set-error.zeek, line 9: &default is not valid for global variables except for tables (&default=10)
-error in /home/jon/pro/zeek/zeek/testing/btest/.tmp/language.attr-default-global-set-error/attr-default-global-set-error.zeek, line 9: &default is not valid for global variables except for tables (&default=9)
-error in /home/jon/pro/zeek/zeek/testing/btest/.tmp/language.attr-default-global-set-error/attr-default-global-set-error.zeek, line 9: &optional is not valid for global variables (&default=9, &optional)
-error in /home/jon/pro/zeek/zeek/testing/btest/.tmp/language.attr-default-global-set-error/attr-default-global-set-error.zeek, line 10: &default is not valid for global variables except for tables (&default=set())
+error in /mnt/data/tim/zeek/testing/btest/.tmp/language.attr-default-global-set-error/attr-default-global-set-error.zeek, line 4: &default is not valid for global variables except for tables (&default=0)
+error in /mnt/data/tim/zeek/testing/btest/.tmp/language.attr-default-global-set-error/attr-default-global-set-error.zeek, line 9: &default is not valid for global variables except for tables (&default=10)
+warning in /mnt/data/tim/zeek/testing/btest/.tmp/language.attr-default-global-set-error/attr-default-global-set-error.zeek, line 9: Found duplicate tag &default
+error in /mnt/data/tim/zeek/testing/btest/.tmp/language.attr-default-global-set-error/attr-default-global-set-error.zeek, line 9: &default is not valid for global variables except for tables (&default=9)
+error in /mnt/data/tim/zeek/testing/btest/.tmp/language.attr-default-global-set-error/attr-default-global-set-error.zeek, line 9: &optional is not valid for global variables (&default=9, &optional)
+error in /mnt/data/tim/zeek/testing/btest/.tmp/language.attr-default-global-set-error/attr-default-global-set-error.zeek, line 10: &default is not valid for global variables except for tables (&default=set())
diff --git a/testing/btest/Baseline/language.duplicate-attributes/out b/testing/btest/Baseline/language.duplicate-attributes/out
new file mode 100644
index 0000000000..422d5f94e1
--- /dev/null
+++ b/testing/btest/Baseline/language.duplicate-attributes/out
@@ -0,0 +1,2 @@
+warning in /Users/tim/Desktop/projects/zeek/testing/btest/.tmp/language.duplicate-attributes/duplicate-attributes.zeek, line 6: Found duplicate tag &default
+warning in /Users/tim/Desktop/projects/zeek/testing/btest/.tmp/language.duplicate-attributes/duplicate-attributes.zeek, line 6: Found duplicate tag &read_expire
diff --git a/testing/btest/language/duplicate-attributes.zeek b/testing/btest/language/duplicate-attributes.zeek
new file mode 100644
index 0000000000..b25a45d033
--- /dev/null
+++ b/testing/btest/language/duplicate-attributes.zeek
@@ -0,0 +1,6 @@
+# @TEST-EXEC: zeek -b %INPUT >out 2>&1
+# @TEST-EXEC: TEST_DIFF_CANONIFIER=$SCRIPTS/diff-remove-abspath btest-diff out
+
+global a: table[count] of count
+        &default = 10 &default = 9
+        &read_expire = 5 sec &read_expire = 1 min;