diff --git a/data/schema/core/actionwml.cfg b/data/schema/core/actionwml.cfg
index 5613cf344a0e..a7b6113a6dc7 100644
--- a/data/schema/core/actionwml.cfg
+++ b/data/schema/core/actionwml.cfg
@@ -94,12 +94,7 @@
 		name="while"
 		max=infinite
 		super="$conditional_wml"
-		{ACTION_TAG "do" min,max=0,infinite}
-		[tag]
-			name="do"
-			max=infinite
-			super="$action_wml"
-		[/tag]
+		{ACTION_TAG "do" max=infinite}
 	[/tag]
 	[tag]
 		name="for"
@@ -261,7 +256,7 @@
 		{REQUIRED_KEY types string_list}
 	[/tag]
 	[tag]
-		name="allow_extra recruit,disallow_extra_recruit,set_recruit"
+		name="allow_extra_recruit,disallow_extra_recruit,set_extra_recruit"
 		max=infinite
 		super="$filter_unit"
 		{INSERT_TAG}
diff --git a/data/schema/schema.cfg b/data/schema/schema.cfg
index 783ea4101383..fa89236fe14b 100644
--- a/data/schema/schema.cfg
+++ b/data/schema/schema.cfg
@@ -92,7 +92,6 @@
 							[tag]
 								name="intersection"
 								min=1
-								{LINK_TAG "wml_schema/type"}
 								[tag]
 									name="type"
 									max=infinite
diff --git a/src/serialization/schema_validator.cpp b/src/serialization/schema_validator.cpp
index 7c95e9e13ff2..c2da3de37e07 100644
--- a/src/serialization/schema_validator.cpp
+++ b/src/serialization/schema_validator.cpp
@@ -128,6 +128,18 @@ static void wrong_path_error(const std::string& file,
 	print_output(ss.str(), flag_exception);
 }
 
+static void duplicate_tag_error(const std::string& file,
+		int line,
+		const std::string& tag,
+		const std::string& key,
+		const std::string& value,
+		bool flag_exception)
+{
+	std::ostringstream ss;
+	ss << "Duplicate or fully-overlapping tag definition '" << value << "' in key '" << key << "=' in tag [" << tag << "]\n" << at(file, line) << "\n";
+	print_output(ss.str(), flag_exception);
+}
+
 static void wrong_type_error(const std::string & file, int line,
 		const std::string & tag,
 		const std::string & key,
@@ -446,10 +458,43 @@ bool schema_self_validator::tag_path_exists(const config& cfg, const reference&
 	return false;
 }
 
+bool schema_self_validator::tag_matches(const std::string& pattern, const std::string& tag)
+{
+	for(const std::string& pat : utils::split(pattern)) {
+		if(utils::wildcard_string_match(tag, pat)) return true;
+	}
+	return false;
+}
+
 void schema_self_validator::validate(const config& cfg, const std::string& name, int start_line, const std::string& file)
 {
 	if(type_nesting_ == 1 && name == "type") {
 		defined_types_.insert(cfg["name"]);
+	} else if(name == "tag") {
+		bool first = true;
+		std::vector<std::string> tag_names;
+		for(auto current : cfg.all_children_range()) {
+			if(current.key != "tag" && current.key != "link") continue;
+			std::string tag_name = current.cfg["name"];
+			if(current.key == "link") {
+				tag_name.erase(0, tag_name.find_last_of('/') + 1);
+			}
+			if(first) {
+				tag_names.push_back(tag_name);
+				first = false;
+				continue;
+			}
+			auto split = utils::split(tag_name);
+			for(const std::string& pattern : tag_names) {
+				for(const std::string& tag : split) {
+					if(tag_matches(pattern, tag)) {
+						queue_message(current.cfg, DUPLICATE_TAG, file, start_line, 0, current.key, "name", tag_name);
+						continue;
+					}
+				}
+			}
+			tag_names.push_back(tag_name);
+		}
 	} else if(name == "wml_schema") {
 		using namespace std::placeholders;
 		std::vector<reference> missing_types = referenced_types_, missing_tags = referenced_tag_paths_;
@@ -551,6 +596,9 @@ void schema_self_validator::print(message_info& el)
 	case WRONG_PATH:
 		wrong_path_error(el.file, el.line, el.tag, el.key, el.value, create_exceptions_);
 		break;
+	case DUPLICATE_TAG:
+		duplicate_tag_error(el.file, el.line, el.tag, el.key, el.value, create_exceptions_);
+		break;
 	}
 }
 
diff --git a/src/serialization/schema_validator.hpp b/src/serialization/schema_validator.hpp
index 2a2128194905..9de368adecf9 100644
--- a/src/serialization/schema_validator.hpp
+++ b/src/serialization/schema_validator.hpp
@@ -182,8 +182,10 @@ class schema_self_validator : public schema_validator
 	std::multimap<std::string, std::string> derivations_;
 	int type_nesting_, condition_nesting_;
 	bool tag_path_exists(const config& cfg, const reference& ref);
+	static bool tag_matches(const std::string& pattern, const std::string& tag);
+	
 	void print(message_info& message) override;
-	enum { WRONG_TYPE = NEXT_ERROR, WRONG_PATH, NEXT_ERROR };
+	enum { WRONG_TYPE = NEXT_ERROR, WRONG_PATH, DUPLICATE_TAG, NEXT_ERROR };
 };
 
 } // namespace schema_validation{