Multiple plants in one pot.
I bought a plant on Ebay with 15 bbulbs. It was shipped in its pot and as I do with all new plants, as soon as I got it, I took it out in order to clean the roots, inspect for parasites and then repot or mount it in fresh surroundings.
This plant, which looked like a normal, strong 15 lead grower, immediately fell apart into 2 equal halves. Apparently 2 small plants were started off back to back to arrive at the current state of affairs faster.
I complained to the seller and offered to send it back and accept a similar plant that was again being offered. That offer was accepted. Then on a whim I responded again and requested that the new plant be mailed bare-root in order to avoid a repeat performance. The answer was that no doubt this also would be 2 plants, would I agree to keep the 2 I have and accept a 50% refund. That seemed reasonable and we are done, everyone, at least at this end, is happy.
Obviously this grower/nursery knew that this method was being used to create larger looking plants in a shorter period of time. They were fair about it so I won't identify them but it behooves everyone who receives new plants from any source to unpot them and start with fresh whatever (coconut, bark, moss etc). Gives you a chance to view the roots, check for bugs and discard old bark. Also tells you if you have more than one plant.
I got a Dendrobium once, in a basket, which when it bloomed, had different colored flowers on 2 sides of the basket.
The disadvantage of having 2 plants side by side is that they may not be exactly the same, may not bloom at exactly the same time and are ineligible for awards. 2 small plants are not as strong as one large plant.
I must admit I am guilty of this also, the most glaring instance was a big floofy cat, BLC White Eagle 'Eagle King' where I stuffed 4 young plants in a pot. When they grew up, they had a perfect bloom one year, just in time for our fall show and with 14 beautiful flowers close together won 'Best of Show'. I did not say anything and took my trophy home. I hope I won't burn in orchid hell for this. I also have several groupings of young plants right now where I'm doing this on purpose to create an effect.
If you do it on purpose for your pleasure its one thing, when you buy a plant and instead of one large you actually get 2 small, its not OK. Something else to watch out for.