willsandestateslawyersblog.ahbl.ca/2017/01/12/a-tale-of-two-wills-when-and-why-dual-wills-are-an-effective-estate-planning-tool/
See also:
www.pallettvalo.com/whats-trending/what-effect-does-a-general-revocation-clause-in-a-will-have-on-prior-beneficiary-designations/