If it’s just for a short while they should be fine! I think it would be ideal to let them stay within sight of each other, so you could set up a temporary pen for training in their main area. Or just lock one away in the pen while the other is being trained in the free-roam area nearby (I have had to do this recently to feed my elderly bun without his bonded mate eating all his food).
You probably wouldn’t want to regularly do something like taking one rabbit out of sight and smelling range away for a long period, such as to run obstacles outside. If you did start training at that level, I would bring the other bun in the carrier along for the ride, so they ride to and from the destination together, and hang out together during downtime.
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The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.