After doing research on an alien medic you would get the live research of that same live alien and a random live or autopsy from another alien race. The thing is that the "actual" autopsy/interrogation does not fill research requirements and also still appears in the research tab like you didn't got it before.
Here's an example. I researched an aquatoid medic, and has a bonus i got the calcinite autopsy. However, vibro blade didn't became available for research. Later on did calcinite autopsy (the normal way) and it unlocked the vibro blade.
Even if you get the ufopedia from the research, the game doesn't consider it was actually done, so it will not fill requirements.
I haven't tried this on xcom1 but it might have the same glitch.
What do you think guys? A fix for this would be complicated?