Hi again @denmark.daya,
Unfortunately, one Auth0 database connection cannot simultaneously do lazy migrations from two sources.
But since you specified that you have two different apps with two distinct pools of users, I suggest having two database connections for each database and doing the lazy migration separately. After all accounts have been migrated, you can export users from one database to another if unifying your databases is the end goal.
If you have any other questions, feel free to reach out.
Have a good one,
Vlad