Is it permissible to make a backup copy of a protected educational disc for personal use, knowing that it deteriorates quickly and can be copied with licensed software?

As long as you have purchased an original copy, there is no harm in duplicating it for your personal use and to benefit from it should the original copy be damaged. What is prohibited is copying it without purchasing an original, or copying it for commercial purposes, and similar actions that deprive its owner of their intellectual and material rights.