How can I import one machine history data to another machine. I want to copy all historical data of trends & reports onto another machine.
I have copied the Data folder of my application to my another application and replace the folder but I'm not getting Historial data inti it.
Is there any extra steps needs to perform here?

Can you be more specific on what you are looking to do here? Assuming both machines are running VTScada, you can simply do a get from server and then add both machines to the server list. There will sync their history. If you remove the list, each machine should retain it's data.

You can also copy an application directory to anywhere and point to it again using the add existing application option when creating a new application.

Do either of these solve your problem?

If you are looking to export some data from one application and move it into another application (or from another scada software into VTScada), check our the following:

https://www.youtube.com/watch?v=NN_YGMpKxKU

Yes, that is the option Get from the server changeset but both machines are on different networks totally.
In my case in one of the machines, the data is locked now and I want all this History data on my other machine.
What should I do in this case?

Copy the entire application directory to the new PC (It's typically in the VTScada/ApplicationNameNoSpaces directory but you can find it from the application info tab in settings). You can paste it right into the VTScada directory. From there add a new application using the following options:

Advanced->Find Existing->Point to it

Then select next and go from there. That will be the entire application with history.

I should add that, assuming the application was secured, you'll need the correct security credentials to run the application.