I am running Minecraft 1.6.0.6 beta on my Redmi note 4. 32/3 GB edition.

I found a skeleton dungeon near the surface while exploring and since I had need of arrows I made a skeleton farm out of it. A 9x9x7 room with spawner in the centre and a row of water blocks to funnel the skeletons down a corridor where I sat one block below the skeletons and killed them with my Sharpness IV, Mending I, Fire Aspect I, Unbreaking III and looting III, Diamond Sword. Took me 2 hits. With all the exp, the sword was unbreakable.

Since the main motive was to collect arrows, I was quite irritated that the skeletons were dropping their bows with an unusually high chance. Same with their equipment. But no arrows.
I was afraid that this was the result of the double drop add-on I had installed on that world for an hour while farming blazes to get double blaze rods. But it was a few days ago, and I had removed it after coming out from the nether.

So to test this, I used an already created creative world to construct the structure. After killing more than 300 skeletons I found that all the skeletons had a near certain chance to drop their enchanted bows. Normal bows had less chance. Equipment had a nearly 80-90% chance of dropping. Bones very rarely and only one skeleton dropped 2 arrows.
Since the double drop add-on was installed only in the survival world and this creative mode world showed the same results, the fault was not in the add on.

The drop rates of other mobs might be messed up as well, but I have only verified this one.

I would really appreciate any help in resolving this.
I cannot farm for arrows this way!