Qs. about input claim

Scene1. I filed july3b and ommit one purchase bill to claim input. 

Scene 2. I filed the August 3b and claim one purchase bill which was already claimed in july 3b. 

Qs1. Can i claim input of the omitted bill in sept3b? 

Qs2.what will i do with the  same  bill that i claimed in july&August? 

Qs3. Can i claim input in sept3b by subtracting the bill which i was already claimed 2times? 

Pls help me?