The trademark must be distinct and unique. If other company is already using such phrase then one must not trademark the same. They gain the goodwill from such phrase. Hence, they have market value for it. Due to which the other company can sue for the passing off the trademark even if they have register the trademark. So one should not use the trademark of any other person whether it is registered or unregistered.
LegalWiz.in guides you about the availability of trademark by doing a search of the brand name before making application.