I’ve personally done the following:

  1. Buy a large ticket item (e.g. furniture).
  2. See an ad on Amazon for a different/nicer/better/faster shipped version.
  3. Buy it.
  4. Cancel the old order.

Is that a common pattern? No idea. But it’s not crazy to me that it happens often enough that it’s worth it to Amazon to show similar items to people who already bought them.