Yes, proceedings under sec 138 and under sec 420 IPC can be initiated separately. 

Yes, you can file both the cases simultaneously under NI act as well as criminal law.

I concur with the opinion and advise of learned senior experts, both the cases can be initiated and proceeded simultanously before jurisdictional Judicial Magistrate First Class.

However, police shall not help you in criminal complaint u/s 420 IPC, for that you will have to move to the Magistrate. 

J.C.Vashista Sir, 

I did not get your below words. if I approach police now they are not going log 420 case ? Do i have to approach anyone else ? if so directly or through my lawyer ?

"However, police shall not help you in criminal complaint u/s 420 IPC, for that you will have to move to the Magistrate. "

Every alleged offence of cheque bounce does not involve "cheating" as defined under Section 420 CrPC.

Dear Ravichandra,

I have already mentioned in my opinion / advise to approach area Magistrate for a complaint u/s 200 CrPC, however, police can not / shall not take any action if you want to get a FIR registered for the offence of dishounor of cheque  

P.Venu Sir 

how to differentiate which cheque bounce is called as cheating and which cheque bounce is not called as cheating ? could you pls throw some light. Your reply on this will be very helpful in educating people like me. 

Vashista Sir,

Thanks for your reply. I did not understand anything. however I will show it to my local lawyer( who happens to my childhood friend and new to lawyer profession). Here problem is courts taking lot of time..infact years and years and years.  Thats why even after we preparing for NI act I am enquiring about 420 case.