Triple stem avocado seedling

I"ve had avocado seedlings die and then sprout a second trunk. I've even seen the second trunk die and a third one come up. But i've never seen two trunks at a time. I've just had one shoot 3 healthy stems up. Is this common?

We start every avocado pit we come across, all as indoor plants. We currently have about 22 pits in water, two of which have stems and roots, and another dozen in the process of splitting and rooting out. We have eight potted, in various stages of growth, the oldest being four years, and taller than I am.

I have seen this action twice. Once, a primary came up first, followed by the other two, one after the other. The secondary and tertiary stems died eventually.

-CK

It's a polyembryonic seed.  I have one that I started a few months ago and it has put out at least 4 stems, 3 of which I pinched off right away to allow the biggest one to grow.  There is also a seed-grown avocado on my land that the previous owner planted, which is now about 8 feet tall.  When I first moved in, there were 3 of them within 1 square foot, all very leggy, not a lot of new growth at about 6 foot tall.  I cut down the 2 smaller ones and now the one that's left is growing beautifully, and a few new suckers have since come up near the base, which I removed.

Interesting bit of info I found on google just now:

"The old type Avocados can also be raised from seed if they are polyembryonic, meaning that a seed produces several stems. A polyembryonic seedling is worth keeping. If it is monoembryonic (single stemmed) you don't know if the tree will be a good producer or not."

Being polyembryonic... Does that make the trunks siblings rather than identical triplets?

First shoots on polyembryonic mangoes are usually identical or close to the genetics of the original tree  and have similar fruiting qualities, but  I had always been under the impression that avocado seedlings had more or less reverted to the massive background genepool they came from and were unreliable (but potentially brilliant!) for fruit quality. This thread has made me  look into the subject more closely and reveal even more of my ignorance. Thanks very much! Next time I find a multi-shooting avo seed I will surely grow it on and see what happens! Does anyone know if the first shoot is clonal and next shoots sexual as is the case with polyembryonic mangoes?

I transplanted the seedling into its long term (hopefully it will survive) home, and here it is with its root. Just a single taproot. Does this mean it is not polyembryonic?

The triplets are doing fine after 11 days in the ground...