If you are switching back and for between 2 gun barrels, no.

The additional scope is a good idea.
I recommend buying a Nikon Prostaff as a backup, they run just a little over $100 new, plus if you end up not needing it, theyhave a pretty good resell value.

As far setting up a second scope a spudded bore sighter can have you close to dead on, before you even leave the house.