mobile

recently I've bought a galaxy tab s 8.4 , but take too mach time (about 6 hours) to charging with it's stock charger (5.3 v , 2.0 A) , when i charged with note 4 charger (5 v , 2.0 A) , it charged normal (about 2.5 hours)
now i have two questions :
1. the note 4 charger is suitable for my device ? isn't bad for battery life ?
2.is it possible that the stock charger was fake !!!???