Table Replica

I have one table with some check constraint and it is not allowing me to insert data if i do not pass the values for check constraint.

I have created the replica of that table with check constraint and passing null as check constrainit it is allowing me to insert data

How is that possible, please suggest

Show us the DDL for both tables, including the constraints. There is something different. Probably one has NOT NULL, and the other is NULL.