1 signal mirror is plenty.
1 heatshield is enough.
3 ways to make a fire ... is more than enough.

You've got to cut weight. I used to try to double up on items (for backups), but more and more I don't do that now - EXCEPT for some critical equipment.

Instead I do the following:

1. Make sure critical items are tough - industrial strength. So they won't break during normal use.
2. Rely on organization. You shouldn't be losing essential gear. Cut weight, and step up your organization.
3. Double-check that you've got all your gear, every time you leave your last rest point.
4. Rely on personal skills to improvise gear, if my stuff gets lost or broken.
5. Don't freak out if you're missing something. Stay cool, keep your sense of humor, adapt.

Just my 2 cents worth.

other Pete