Our animations are made in maya and then imported into unity. If we add animation events to them then the next time the animations get updated and reimported then the events will be gone.
Is there a way to prevent this from happening?
It seems loading a new animation creates a new one, hence the (1) addition clearly showing it is not overwriting the original one.
If you right click your animationName.anim, you are given a long yaml file with all the details of your animation.
At the very end of it you can find the m_Events section. You could copy them and paste onto the new animation.
You could also come up with an editor script that does automatically.