SAFR has the ability to add multiple faces to a single identity.  This is done by using the merge option in the SAFR Person Import window or by selecting 2 identities in SAFR Person window and choosing the "Merge" option. From SAFR Desktop 3.7, you can add face to existing identity from "Add alternate face" popup menu.

This document describes the effect of adding more images of same person.  Here we refer to an "identity" to represent a person.

Multiple images merged in the same identity increase true positives without increasing false positives.

Multiple images in the same identity do not reduce false positive.  This would require composite facial recognition signatures which is a SAFR roadmap feature.

When adding additional faces to SAFR, its important to merge faces instead of add new identities. Increasing number of identities (not faces) increases the chance of false-positive match since statistically in  large population it becomes increasingly easier to find two faces that are alike.