The answer is yes. Notice Hal Jordan rocking Orange AND Yellow. And next to that is Guy Gardner rocking Red AND Star Sapphire. Both these guys are wearing two rings and they're using the powers of both rings simultaneously. From: Emerald Warriors #10 (May 25, 2011)
If I'm being totally honest though, I just found that Googling "two Lantern Rings." What I have actually READ is one of the most important events in recent DC print: Darkest Night (2009-2010), and won't soon forget Guy turning into a Black Lantern meat grinder when Kyle Rayner died.
There are other instances of two rings being worn simultaneously and in most one can see one color being dominant based on the dominant emotion (i.e. Guy in the above picture have more Red than Green due to his rage over Kyle's death surpassing his will as a seasoned combatant). Hal and Guy in the first photo are consciously channeling both equally as they had a mission to accomplish, picking the Rings themselves, which is extraordinary as the Power Ring(s) generally find a suitable member to their respective Corps.
I present Harley Quinn rocking a Black/Red ring. You read that right two corps, one ring. From: Harley’s Little Black Book #2. (February 10, 2016) Notice her coloring is not only equal, but it is checkered, I would take that to mean that the merged ring keeps the wearer evenly powered (yes, the rings have unique powers) and is more intrinsic to the ring as it's colors are visually woven together. But perhaps I am reading too much into it.