If you want to change your own will back to a previous version, consult a legal professional about the correct way to do so.
I've been to two legal professionals (solicitors in the UK) and I got different answers.
One says "yes" and quoted section 20 of the Wills Act 1837.
The other said "no". and said there is some case law (not given) that stated the first paragraph of the (destroyed) revoked Will states "I revoke all previous testamentary dispositions".
I'm open to suggestion on which solicitor is correct