I would have to assume it would be people splitting up the observations rather than the observations being done by only the shopper they are contracted with. So, for a possible example, a gas station shop where the shopper is to go inside, interact with the associate and make a purchase and observe the inside, restroom, outside, pumps etc. One person goes does the inside and restroom while the other does the outside and pumps gas. Both take photos of 'their part' of the shop. The passenger is the shopper and inputs the shop as the driver drives to the next location.
Another possible example is having multiple shoppers working under one shopper number. In the past CORI would raise the fee on shops when you took certain numbers of them per month all at the same time. It seems to me that the per shop fee was raised $3 per shop if you performed 100 of them. Shoppers would make routes of them. A Team approach might divide up the 100 shops into smaller groups with different observers doing the reporting and each benefitting from the bonus while not needing to perform a full 100 shops themselves.