Brothers Rory and Richie Arnold will renew a 27-year rivalry when the 208 centimetre identical twins team up for the first time in six years when they compete for the same spot at the ACT Brumbies.

The good news is their mum and dad won't have to play favourites after Richie joined Rory in Canberra after the demise of the Western Force.

The bad news, for the other Brumbies locks at least, is that they have no intention of showing brotherly love at training and will draw on years of backyard cricket bust ups for extra motivation.

"I would always get him out with electric wicket-keeper, but he'd never walk. There's been some good [fights], that's for sure,"Richie said with a grin before Rory jumps in.

"Everything always started off pretty friendly. But it didn't take long before we were steaming in to bowl bouncers at each other," Rory said.

"Not long after that there were the punch-ons for whatever reasons. It was pretty brutal. But it was just what brothers did and we were back out there playing again the next day.

"We didn't think we would be here together, and thinking about how far we've come. I can't wait until the New Year for when I can get out there and do some training with him."

The Arnolds have walked very different paths since they were plucked from the pub by a club rugby team in Murwillumbah in 2010 to start their Super Rugby journeys.

Rory was recruited to the Brumbies and made his Wallabies debut two years ago, but injury delayed Richie's rise before playing his first game for the Force this year.

The Australian rugby axing debacle opened the door for them to team up in Canberra, creating the confusing nightmare for commentators, fans and even Brumbies coaches.

When Brumbies coaches thought they saw Rory, who is recovering from a thigh injury, run out for full-contact training they had to intervene to make sure he had been cleared by medical staff.

"But it was Richie. He got a haircut a couple of days before that and they thought I was out there when I wasn't supposed to be," Rory said.

Rory reckons the brothers are easy to tell apart because, "I've packed more scrums than him, so he looks taller. That's what the boys are saying anyway."

But when Richie was in Fiji earlier this year for a National Rugby Championship game and the locals thought he was Rory, he went along with it.

"They all said: 'You're Rory Arnold, Wallabies player'. I just smiled and went along with it and got some photos," Richie said.

Richie's arrival at the Brumbies has added spice to an already intense battle for lock spots in the starting side for next year.

Rory and Brumbies skipper Sam Carter were the regular starters this year, while back-up Blake Enever made his Wallabies debut on the end of year spring tour of Europe.

Add Richie and young gun Darcy Swain to the mix and all of a sudden new Brumbies coach Dan McKellar has a second-row selection headache.

Rory is expected to return to full training duties in January after having surgery to repair his injured thigh, which was first diagnosed as a knee injury and prematurely ended his Wallabies season.

Richie has already thrown himself into Brumbies preparations and is hoping to make a name for himself, admitting he never thought it was possible he and his twin brother would be professional athletes.

"I was a bit of a mess when I finished school, I think I was 208 centimetres and 135 kilograms," Richie said.

"Seeing Rory go well and how fast he climbed the ranks definitely fuelled the fire. I'm excited to be in Canberra, we've got some good depth at lock so I think that's only going to be a good thing.

"Back when we were in the pub, I thought Rory was talking trash when he said he was going to play rugby when the guys asked him to.

"A few weeks later we went down to training and now here we are. It's pretty crazy."