CommentStreams:D58879240b0f941d146138486bbdd167

My guess is a buffer in case somebody messes up by accidentally selecting a 6th copy of an artifact, or if the game bugs and fails to give you one.

In a previous event I actually ended up missing two artifacts, so even after clearing L16 I was short one copy. The developers were completely unresponsive to my bug reports/requests for customer service, so I would guess they simply don't resolve these problems.

So the extra shot is probably a minimum buffer against player error or buggy code.