If you have created 2 accounts and want to gather your training data altogether in one of the accounts, follow the below process:

1. Log in to one of the accounts.
2. Go to Settings > My account > Sign out
3. Sign in to the other account.
4. Select the first option: "Combine and save all my training data from both my device and my account"

5. Tap "Sync my training data"

You're all set!