I dont think its about boredom,  I think its just a natural response to the presence of another rabbit. Most animals, except dolphins, possibly other whales, perceive their mirror image as another animal. I’ll never forget when my dog saw herself in a wall mirror for the first time. She was just a pup. Her face lit up with delight at the sight of the other puppy and she ran up to it -just to be met by a sheet of cold glass. The surprise and disappointment in her face is still painful to recall.

Your bun will probably get used to the scentless, noiseless bun in the mirror and lose interest in it.

Yes, your bunny is probably just wondering who this intruder is and why they won’t go away. As Bam said, bunnies often lose interest after awhile.