Does a DVD multi drive burn a dual layer DVD?

This really depends. This specific capability is usually written out on the specs list of your drive. You can also check the burn speeds list - if anything there has the suffix "DL", that would mean "dual layer" - for example, if it says 8X DVD-R/DL - that means it burns in 8X speed for DVD-R, and also 8X in Dual Layer mode.

My DVD burner, an external DVD burner by DIGISTOR(digistor.com) - burns 8X in single layer and 6X in dual layer. Your drive has to specify if it can do dual layer or not. There is no automatic distinction. Check the manufacturer's website or the literature that came with your drive.