i have learned that " Contrary to patents, trade secrets are protected without registration, that is, trade secrets require no procedural formalities for their protection. A trade secret can be protected for an unlimited period of time, unless it is discovered or legally acquired by others and disclosed to the public. For these reasons, the protection of trade secrets may appear to be particularly attractive for certain companies. There are, however, some conditions for the information to be considered a trade secret. source
So, if a competitive company stole an idea from another company and says it has discovered such idea, what the original company have with them to demand the Intellectual property, as they haven't registered or disclosed certain idea.