Q.My dendrobium orchid produced 2 keikis. Advice please!
I bought it from a nursery about a year ago, but they had it planted in regular soil,which I had never seen before. I always plant in a bark mix. But I left it alone, kind of an experiment! Now 2 keikis have sprouted near top of plant. Is it from stress? And should I leave them be or replant them? They both look healthy. Will they eventually kill mother plant? Thank you for any help!

You are right to be concerned about the potting mix for your Orchid, it is a good idea to change it out to a good quality Orchid potting medium and a suitable Orchid pot.
These links will give you information on this.
https://www.gardeningknowhow.com/ornamental/flowers/orchids/repotting-orchid-plants.htm
https://www.gardeningknowhow.com/ornamental/flowers/orchids/orchid-planting-mediums.htm
Congratulations on the new Keiki's!
They will not harm the parent plant, but you need to make sure they are mature enough to be removed and repotted.
This link will help you with this task.
https://www.gardeningknowhow.com/ornamental/flowers/orchids/how-to-plant-an-orchid-keiki.htm