Upon the new clean installation, Sitecore 9.1 puts the following certificates (as per below example of habitat project hostnames):
1. Current User\Personal - nothing
2. Current User\Intermediate Certification Authorities - SIF
- Sitecore Install Framework / Sitecore Install Framework
3. Local Computer\Personal - xConnect and Identity Server
- habitat_xconnect.dev.local / DO_NOT_TRUST_SitecoreRootCert
- habitat_IdentityServer.dev.local / DO_NOT_TRUST_SitecoreRootCert
4. Local Computer\Intermediate Certification Authorities - Sitecore and SIF
- DO_NOT_TRUST_SitecoreRootCert / DO_NOT_TRUST_SitecoreRootCert
- Sitecore Install Framework / Sitecore Install Framework
Hope this helps!