The club does not reuse membership numbers (give old numbers to new members) but will reissue them to folks whose memberships have lapsed. For those who have been away for more than five years, we usually issue a new number unless the member notes their original number on their membership application. Several years ago the club upgraded their membership software (we went from index cards to a computer) and all lapsed memberships were not carried forward due to the sheer volume of expired memberships.
So, for those who were at one time members, if you rejoin and want to use your old number you can, just make sure you let the membership secretary know you'd like to do so. As Fid mentioned, it can be done!