No, it won’t overwrite your original campaign. Instead, it pauses your original ad groups and activates the new ones from Tenscores that will have a "TS" prefix.
The prefix is added so you can revert the changes anytime by pausing those ad groups created by Tenscores and reactivating your original ones if you're not happy with the results.
No other settings are changed by Tenscores, only the addition of new ad groups, or new ads is handled by Tenscores.