Yes it is allowed,but can cause trouble if you do not RP what your ID is. I have a Junker WRECKER-J,and in the past my Lib cruiser was just WRECKER. It caused many issues so i renamed the Cruiser.
Also it is possible someone just chose similar name. I fly a Lib Dread Yorktown. Since i made my ship i have seen a LNS-Yorktown,and a HMS-Yorktown. They are different players,but i have had players try to take vengence on me for what they have done.