If you surround a map with a stack of paper in every slot in crafting table after the fird time crafting a map paper number changes to 122 instead of 61

What I expected to happen was...:
the number of paper in each slot should be 61

What actually happened was...:
the number of paper in each slot is 122 and after you've crafted a map one more time 242

Steps to Reproduce:
1. put a map in the center of crafting table and surround it with full stack of paper in each slot
2. take the crafted map and put it in the middle of crafting table 
3. repeat step 2 two more times and you'll see the nuber of paper in each slot is 122
4. do it once more and the number of paper is 242 instead of 60