Completing both a SF 85 (TIER 1) and SF 85P

Has anyone ever been required to do a Tier 1 (SF 85) investigation to get a CAC and computer access and then needed to complete an SF 85P afterwords? The company says I will need to do a public trust investigation but the onboarding government personal is saying I need to fill out SF 85 for a tier 1 investigation to get a CAC and computer access. Will I also have to do the sf85p if already completing the SF 85 for the tier 1 investigation?

Are you concerned about the SF85p for some reason?

No, I just find it strange that I am getting mixed information on completing an SF85 by my onboarding contact but my company said to prepare for an SF 85p.

whats a CAC ?