The model you picked is the model in every frame.
One face across the whole run is what makes a hundred items read as one shoot. Identity is checked per frame against the reference you selected, and each model reference serves its own block of items so a batch never mixes faces mid-set.
The failure that named it A stranger appearing in the middle of a set reads as a mistake rather than a choice, and it is the failure nobody catches until the PDPs are live side by side.