No snapshots are not destroyed when a snapshot is restored. They are kept for as long as your retention policy is set for.
If you are using SnapShooter to manage your droplet and you need to restore your Digital Ocean it can be worth pausing backups to make sure your old backups are not destroyed until your happy you have fixed the issue.
How to pause backups
Select the droplet you wish to pause
On the top right press the pause symbol
You should see the confirmation message "Your droplet snapshot schedule have been pause"
Your droplet is now paused and will have a status of paused. No more backups will be scheduled and no old backups will be removed.
How to unpause/resume Backups
Select the droplet you wish to resume
On the top right press the play symbol
You should see the confirmation message
Your droplet snapshot schedule have been resumed
Your droplet is now resumed and will have a status of activated. Backups will continue on scheduled and old backups will be removed based on your retention policy.