Yes, both apps can be used simultaneously, however there is no check in place for the same product being loaded by both apps. Thus, if the same brand is enabled in both the Turn14 app and the Slingshot app, then you will encounter duplicate products loading into your store.
We recommend only enabling a brand through one of the two apps at a time.
If you are using both apps, please remember to reach out to Support@dataheretothere.com to have bundle pricing applied to your account.