Unfortunately not, if you have over-typed an existing email campaign with new text and changed the layout then once you have clicked the Save button this will save the new version and over-write what was the original email.
Please remember to use the duplicate icon instead of editing an existing email campaign that has already been sent.
Click on the duplicate icon as shown below in red to duplicate and rename - that way you will always have a standard template to work with containing logos and links.
When you duplicate an email ALWAYS use the duplicate listed first and then go in and rename the template - press the F5 key when viewing the main list and it will update the name of the campaign for you.
NEVER go into an old email and over-type into it as there are report statistics which will be associated to the original campaign and if you over-type into this email template and resend it will mess up your reporting stats by adding them to the old report statistics total.