Factory accounts

Our Company Accounts maintain by Two Way... One Way at Head Office and another Way at Factory i.e factroy expenses 

Finally Factory accounts will marge with Head Office accounts through Factory Trial Balance and make Company Balance Sheet.

But recently our Company  Opened a New  Bank Account for Factory Accounts purpose only and accordingly all transactions of New Bank Account are entered in Factory accounts..... But some Accounts Entry problem is arised at Factory Accounts.-----

Problem Details : Suppose : Head Office Bank is -- "'A'"and Factory Bank is '"B"" ---- When Head Office doing Fund Transfer From Head Office Bank "A" to Factory Bank "B" then our Accounts Manager informed that this is a Mandatory  Contra Entry due to two banks are under same Company and this Contra entry never changed ... Now question is how to make entry  in Factory Bank Book. If Head Office Fund Transfer is showing under Factory Account  instead of Contra Entry then there is no Problems.

Please reply me  (a) Said Contra Entry is Mandatory yes or no ?? If yes how to make entry in Factory Bank Book

Thanks ......