A project is the umbrella for all of your prospecting and outreach. Each projects has its own Inbox, Pipeline and campaign dashboard. Projects enable you to separate your campaigns, users, and email accounts. This allows for organisation as you scale up your outreach.
For example, if you’re working with multiple clients, you would create a dedicated project for each client, which will then house all relevant campaigns, users, etc.
Deduplication happens on the project level - the same opportunity will not show up twice in the same project as long as dedupication is turned on in the advanced settings.