There are no regulations that fall within OFCCP's jurisdiction that would prohibit that practice. The federal government posts jobs this way, too (www.usajobs.gov). The impact of combining the pools comes when OFCCP observes adverse impact. Typically, where you have job group level adverse impact in hiring (e.g. In Job Group: 2-Professionals, male applicants are significantly more likely to be selected than female applicants) and employees apply to specific titles, the next data refinement would be to separate applicant pools by job title. In this case, OFCCP would likely count the candidates both as Level 1 candidates and as Level 2 candidates. If the application allows the candidate to apply to Level 1, Level 2, or both, they would be added to their respective pool(s). You might also want to add an applicant screening to assess ‘Meets Basic Requirements for Level 1' or 'Meets Basic Requirements for Level 2’ to clearly define your Level 1 and Level 2 applicant pools. Whether a contractor includes the double-count at the job-group level analysis or not seems reasonable either way as long as it is done consistently. OFCCP doesn't regulate the specific way a contractor conducts their internal audit. That said, some companies do opt to post them as separate jobs, in order to not comingle applicants and clearly delineate their applicant pools.
You can use this OFCCP audit checklist to ensure you're doing what is required to maintain OFCCP's regulations including VEVRAA, Section 503, and EO 11246. Or request a demo to streamline your compliance and recruiting efforts.