diff --git a/scripts/base/init-bare.zeek b/scripts/base/init-bare.zeek
index 547234ecbe..d28ab9a13e 100644
--- a/scripts/base/init-bare.zeek
+++ b/scripts/base/init-bare.zeek
@@ -3493,8 +3493,6 @@ export {
 		free_space_start_filtering : int;
 		## minimum amount of free disk space required to continue document filtering
 		free_space_threshold       : int;
-		## minimum amount of free disk space required to continue document filtering
-		free_space_threshold       : int;
 		## default per-user disk quota
 		delete_quota_threshold     : count;
 		## default per-user disk limit
diff --git a/src/Type.cc b/src/Type.cc
index 222d84c62d..60eedfe24f 100644
--- a/src/Type.cc
+++ b/src/Type.cc
@@ -1039,6 +1039,16 @@ void RecordType::AddField(unsigned int field, const TypeDecl* td)
 	ASSERT(field == field_inits.size());
 	ASSERT(field == managed_fields.size());
 
+	if ( field_ids.count(td->id) != 0 )
+		{
+		reporter->Error("Duplicate field '%s' found in record definition\n", td->id);
+		return;
+		}
+	else
+		{
+		field_ids.insert(std::string(td->id));
+		}
+
 	managed_fields.push_back(ZVal::IsManagedType(td->type));
 
 	auto init = new FieldInit();
@@ -1106,7 +1116,7 @@ void RecordType::AddField(unsigned int field, const TypeDecl* td)
 
 bool RecordType::HasField(const char* field) const
 	{
-	return FieldOffset(field) >= 0;
+	return field_ids.count(field) != 0;
 	}
 
 ValPtr RecordType::FieldDefault(int field) const
diff --git a/src/Type.h b/src/Type.h
index 28febf5025..2b7f4d3a29 100644
--- a/src/Type.h
+++ b/src/Type.h
@@ -725,6 +725,7 @@ protected:
 	int num_orig_fields;
 
 	type_decl_list* types;
+	std::set<std::string> field_ids;
 	};
 
 class FileType final : public Type
diff --git a/testing/btest/Baseline/language.record-duplicate-fields/.stderr b/testing/btest/Baseline/language.record-duplicate-fields/.stderr
new file mode 100644
index 0000000000..6f006bb79d
--- /dev/null
+++ b/testing/btest/Baseline/language.record-duplicate-fields/.stderr
@@ -0,0 +1,3 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+error in <...>/record-duplicate-fields.zeek, line 7: Duplicate field 'a' found in record definition
+
diff --git a/testing/btest/language/record-duplicate-fields.zeek b/testing/btest/language/record-duplicate-fields.zeek
new file mode 100644
index 0000000000..4991572b8e
--- /dev/null
+++ b/testing/btest/language/record-duplicate-fields.zeek
@@ -0,0 +1,13 @@
+# @TEST-EXEC-FAIL: zeek -b %INPUT
+# @TEST-EXEC: TEST_DIFF_CANONIFIER=$SCRIPTS/diff-remove-abspath btest-diff .stderr
+
+type test: record {
+	a: count;
+	a: string &optional;
+};
+
+event zeek_init()
+	{
+	local a = test($a=5);
+	print a;
+	}