When Two Affiliate Placements Reach the Same People

A media buyer can purchase two newsletter placements and reach fewer new readers than either sales sheet implies. Before paying the same rate for the second slot, ask whether the seller can report combined unique reach for both placements on the same basis.

Price the extra reach separately

Suppose a seller estimates that placement A reaches 12,000 people, B reaches 8,000 and the pair reaches 15,000 distinct people. The implied overlap is 5,000. If A is already booked, B adds 3,000 distinct readers. At a hypothetical price of $300 for B, the incremental cost per thousand new readers is $100. Dividing by all 8,000 would answer a different question.

Use the same date range, geography and identity definition for all three counts. Delivered emails, unique opens and people are different units. When the seller cannot deduplicate across lists, record the incremental reach as unknown and avoid quoting a precise figure.

Keep repeat exposure in the decision

A second impression may still sell a product to someone who ignored the first. Track placement-level spend and approved CPS commission, and use a comparable holdout if the seller can support one. The overlap estimate informs the price a media buyer might pay for discovery. It cannot establish how many orders the second exposure caused.