Since the Christmas event I have been keeping track of my 4 uniques for 50 relic turn-ins. I now have 90+ turn ins, and contrary to expectations the turn-in generator is not random. There is a weighted bias for giving some "useless" relics and not giving some "useful" relics. Here are the numbers:
Kakaranthara 14
Snakeroot 11
Skrullos 9
Chthon 9
Wakanda 8
Xandar 7
Subteranean 6
Attilan 6
Armor reality 5
Asgard 5
Chandilar 4
Atlantis 4
Gibborim 2
Lumeria 2
If anyone else has done this, I could combine the numbers to get a bigger sample size. Also, note that all of these turn in results are for 50 stack turn ins, I have no idea if the 10 or 20 stack turn-is are any different.
EDIT: Even with this small sample size the chance of getting Kakaranthara is statistically higher than getting lumeria during my turn-ins. The p values are less than 0.01 with two different stats tests. You can verify if you don't believe me...I mean I could of been very very unlucky with turn ins....I wonder if there are other variables at play like which character you use and how many relics you have and which ones are equipped. But in this sample, not all relics are random.