I wouldn't recommend going with more than one instructor unless it's something beyond your control. Going from one instructor to another means that the new instructor wont know what you're capable of and what you still need to learn, so its wasted on getting him/her up to speed.
Each instructor also has their own way of doing things, so you could be doing what you were taught and your new instructor tells you to do it his/her way. Can be confusing, and there's no benefit in going with someone else unless you're unhappy with your current instructors performance.