It is totally possible for a Moringa seed to send up multiple stems. Generally this happens when the plant thinks the first stem isn't going to survive. I have seen a seed send up 5 stems one after the other when a mouse or rat kept eating the new growth!
You can certainly cut down the 2nd stem but it will grow back as multiple stems if you do. If it is indeed two separate trees you can certainly dig it up and replant it elsewhere.
Cutting Moringa stems down to the ground is a technique used to encourage more growth and leaf production. For more information check out my website www.ahealthyleaf.com
. Also you may find it helpful to watch some of my instructional videos on my youtube Chanel