I don't see how you plan to accept (as in sign a contract) with 2 different employers at the same time without getting in some legal trouble due to misrepresenting your intentions with the employers. You may be okay with immigration, but you might get sued by the employers.
It's not clear exactly what you mean by "in the same cap." Each petition will be processed separately, and if you are not already in H-1B status, each approval will reduce the available H-1B 'slots' by one. Depending on the specifics of the individual job offers, it is possible to be approved, and to work for, two H-1B employers at the same time (e.g., two part-time job offers). But if each petitioner does not alert USCIS that there is another H-1B pending for you (and unless each petitioner USCIS's software is more sophisticated than we realize), two approvals in close chronological proximity will deprive someone else of the opportunity to get their petition approved "under the cap."