When you switch from a different attribution provider to Singular, we offer you the unique option of importing your apps' existing user base.
This import allows Singular to mark these users as existing users and keep install numbers accurate. It helps you avoid an "organic spike" when switching to Singular while also protecting you from being billed twice for the same app install.
Note that you must import the historical data into your Singular account before any apps are live in Singular and used for campaigns. If you start running campaigns before you load historical data, there will be spikes in organic installs and the attribution source for some of the devices will be incorrect.