Right-click the file and run it through localized antivirus software or upload it to an online scanning database to ensure it is not a trojan.
Depending on your operating system settings, the actual functional extension is the final one ( .mp4 ). The .mkv might simply be part of the text name. Love Dose 1.mkv.mp4
A file named with .mkv.mp4 generally points to one of three scenarios: Right-click the file and run it through localized