How to display data in form step using structures.

Hi,

1.Can we create 2 forms with same structure in workflow.

     i created first FORM with structure PERNR but when i created second FORM with same structure PERNR it is showing error

       " ABAP source    code  for program XXXXXXXXX cannot be saved ".

2.What type of structures we can use to create FORM ?can we use tables like MARA,MARC..etc ?.

3.what changes we can do in  layout of screen ?.which is generated by form.

4.What is the difference between APPROVE and APPROVE with QUERY FORMS ?

Thanks,

Phani