### Godot version

4.1.0

### System information

Windows 10, i711800H, Forward+ Vulkan

### Issue description

When using @export_group("Name") in a BaseClass, then inheriting from that BaseClass in another class and there also using @export_group("Name"), with the same group name, then running the project and re-saving the inherited class the project crashes with 
```
ERROR: FATAL: Index p_index = 3 is out of bounds (size() = 3).
   at: get (./core/templates/cowdata.h:155)
```

sometimes the editor crashes too after a while.

### Steps to reproduce

1. open reproduction project
2. Run the project.
3. Open the "super"script
4. Press CTRL + S to save it.

### Minimal reproduction project

[MRP_.zip](https://github.com/godotengine/godot/files/12137412/MRP_.zip)

if (base_root.is_valid()) {
					base = Ref<GDScript>(base_root->find_class(base->fully_qualified_name));
				}
				if (base.is_null()) {
					_set_error(vformat(R"(Could not find class "%s" in "%s".)", base->fully_qualified_name, base->path), nullptr);
					return ERR_COMPILATION_FAILED;
				}
				err = _populate_class_members(base.ptr(), p_class->base_type.class_type, p_keep_state);
				if (err) {
					_set_error(vformat(R"(Could not populate class members of base class "%s" in "%s".)", base->fully_qualified_name, base->path), nullptr);
					return err;
				}
			}
			p_script->base = base;
			p_script->_base = base.ptr();
			p_script->member_indices = base->member_indices;
		} break;
		default: {
			_set_error("Parser bug: invalid inheritance.", nullptr);
			return ERR_BUG;
		} break;
	}
	for (int i = 0; i < p_class->members.size(); i++) {
		const GDScriptParser::ClassNode::Member &member = p_class->members[i];
		switch (member.type) {
			case GDScriptParser::ClassNode::Member::VARIABLE: {
				const GDScriptParser::VariableNode *variable = member.variable;
				StringName name = variable->identifier->name;
				GDScript::MemberInfo minfo;
				minfo.index = p_script->member_indices.size();