I am gathering letters of recommendation for my masters graduate program application. Basically, I have been in a lab for 2+ years - the lab is huge, has 50+ research assistants, and is separated into several projects - I was mostly involved with one project. As a result, I was mainly working and interacting with the project manager, not the professor of the lab. On the other hand, I took a seminar class taught by this same professor of the lab, and was doing very well in the class. I was wondering if I could ask BOTH of them for two separate letters of recommendation, one detailing my work ethics and the other detailing my academic performance? I don't really have other professors I'm close with. Just want to see if this is possible at all. Thank you!
Yes, you can ask and will probably be successful at it. You want people who know you well enough to give an honest (and positive) assessment of the likelihood of your success in graduate work, and possibly research, depending on the degree.
Think though about getting letters from a fairly wide range of people if that is possible. But in your case, suggesting to them that they each focus on different things seems like a good plan.