Calling two stored procedures from one, is the order guaranteed?
Yes.  StoredProcedure1 will execute first, and any resultsets from StoredProcedure1 must be consumed by the client before StoredProcedure2 is executed.

It's possible that some client driver or DAL processes all the resultsets and then returns them to your calling code in a different order, but for SQL Server and the Microsoft client drivers, you will get the resultsets in the order in which they are produced.