I'd like to try them out with my gym buddy, is it commonly done in the gym?
Sounds like an incredibly bad idea. Unless you have an extra long barbell, it'll be hard to both get a good grip, and what's going to happen when your friend suddenly drops the barbell halfway through a deadlift? Is risking permanent, severe damage to your back worth it?
People who injure their backs through improperly performed deadlifts often have pain on and off permanently, and not just pain when lifting but constant pain, the kind of pain that will make it hard to concentrate on doing your desk job.
In addition to being risky, it'll also be much worse as an exercise since you won't have the control to push yourself as far as you can when lifting on your own.
And no, it's not common, I've been lifting for 5+ years and I've never ever seen anyone try either.