That combination will look good in the room you described. If each furniture piece has small decorative pillows, swap them so the brown pillows are on the mocha and the mocha on the brown. Moving those twelve inch squares around will change the look of the arranged sofa and loveseat.

Another option would be to go with the sofa and two over sized upholstered chairs or recliners instead of the loveseat. Not because there is a problem with using a sofa and loveseat, or annything wrong with the combined colors. It is presented as just another option for furniture in a living room. These links show rooms where the furniture is a mix of brown and mocha to cream fabrics.

http://picklemedia1.scrippsnetworks.com/...

http://www.vissbiz.com/wp-content/upload...

http://www.skydesigns.us/wp-content/uplo...

http://ldzr.com/wp-content/uploads/2012/...

http://store.furnitureusa.com/media/3b/a...

I think that sounds fine together. You need to add a pop of color to your brown and beige and white room, though. Paint if you can. Add accent pillows of any bright color you like: teal, orange, reds, etc.

I like teals best with your colors.

I moved to a new apartment and I need to get my own furniture so I went to Big Lots and found two pieces of furniture of exactly the same style but different colors. The sofa has the color of mocha, and the loveseat is chocolate brown. Is that a good combination? The living room's carpet is beige and the walls are white.