Where I need to check model number of iPhone is this original or duplicate

This is a user-to-user forum. We are volunteers and not Apple employees.

You can enter your serial number at https://checkcoverage.apple.com/

You should check the serial number at Settings > General >About, matches with your product for example if you have an iPhone 13 Pro Max 256GB in Sierra Blue, this information should match to the serial number exactly if you have a genuine product.

I don’t know what you mean by original or duplicate. And you shouldn’t post personal information in this public user-to-user forum. Your phone was a new retail model when purchased, and was intended to be sold in the US or Canada.

You can enter the serial number here→Apple - Support - Check Your Service and Support Coverage to check the warranty status.