We see what you are asking occurring “sometimes”.
Example: You have a flight from A to B on XYZ airlines. The airlines provide one price through a GDS system. This may or may not include a discount to the agent.
The GDS displays the price which is picked up by the OTA which is displayed on the OTA website.
The airline then provides a promotion on that flight and load it to the GDS system, which is picked up by the OTA, and displayed on the OTA website.
Now you have exactly the same flight with two different prices. Because it is automated the OTA is not aware.
The OTA buys through a consolidator who has yet again a different price for the same flight. But with limited availability, a finite number of seats. So the OTA enables the consolidators inventory to show on their website. You now have three different prices for exactly the same flight.
At Future.Travel we give customers the option to choose the pricing model that fits them. We would offer all three pricing options for the same flight on the same airline on the same day. Sometimes having the lowest cost fair for a flight is important.