Dual stack or Single stack for working with ABAP in Eclipse

Hello all,

Is it necessary to have dual stack system in backend for doing coding in ABAP using Eclipse.
When I was trying to create new project using the dual stack system it is working for me,
and when I try loging in using ECC system it is not allowing me to log in. SO I want to know is it necessary to have dual stack system.
Please provide your valuable help.

Thanks.