Actually, the first oven test did search for organics and failed to find them. That's not big news because scientists did not expect to find organics in the dessicated and irradiated upper layers. They are hoping the next sample, which should be deep enough to scrape up some sub-surface ice might include organics preserved in that ice. The reason for this is that it is believed that water ice would protect organics against the effects of oxides that may have been present.

Also, the reason that the Viking 1 and 2 results were so similar is because the upper dust layer on Mars is ubiquitous to the entire planet.

I, myself, am not very confident we will find organics in the next test. I hope to be pleasantly surprised, but I am fully prepared for an entirely unsatisfactory result.