When I click on a file in Visual Studio I don't get dialog that informs me that "The following files are identical:". It opens immediately compare tool.
Some time ago, I clicked on "Always Open" button on that dialog, and from then onwards VS always opens a compare tool. I use Devarts Code Compare.
How to get back dialog that says that two files are identical?
In Devarts Code Compare tool open Tools > Options > Environment > General. Check "Use binary quick comparison before opening" and the dialog is back next time you compare identical files.