Twins self destruct due to its splash damage. If the distance between you and your target between 1 to 4 metres, then twins will cause self-damage due to it's splash damage hence some times result in a self-destruct. So protection is naturally advisory.
If you want you can remove the splash damage from twins by purchasing "Stable plasma" alteration of twins. Read more about alterations here. https://en.tankiwiki.com/Alterations
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