can we have same name of 2 dialogs in aem ?

You should not use the same name in a dialog (I assume that is what you mean).  As Ravi points out - you would have conflicts.

Best practice for working with dialogs and Granite can be found here - Building Experience Manager Components using Granite/Coral Resource Types

it would be great if you tell more.

Hi,

Can you elaborate more on your requirement ?

Are you trying to have same name for 2 fields in a single dialog ? If so we cannot have same name for two fields as second will overwrite first value and only stores second.