Double jeopardy has to do with a criminal offense; it is not applicable in an employment setting. The fact is that a company can set the conditions of work much as it sees fit. This includes just what disciplinary measures to take against an employee and when. Accordingly, a worker can be put on probation and then later terminated. That is true so long as there is no employment contract or union agreement to the contrary. Also, such action must not constitute any form of legally actionable discrimination.