Where two or more persons are registered proprietors of trade marks, which are identical with or nearly resemble each other, the exclusive right to the use of any of those trade marks shall not (except so far as their respective rights are subject to any conditions or limitations entered on the register) be deemed to have been acquired by any one of those persons as against any other of those persons merely by registration of the trade marks but each of those persons has otherwise the same rights as against other persons (not being registered users using by way of permitted use) as he would have if he were the sole registered proprietor.