Do multiple instances of the Extra Attack feature stack?

The WotC article Unearthed Arcana: Modifying Classes creates the "Favored Soul" sorcerous origin, which grants the the sorcerer the Extra Attack feature at level 6.

Say I made Favored Soul sorcerer go up to level 6, and then multiclassed into Ranger to get its Extra Attack at level 5. Would the two Extra Attack features stack so that I could get 3 or 4 attacks in a turn?