I'm gonna be honest, these two aren't great together. This really started as an experiment. Charlie Puth's "How Long" has a lot of disco-reminiscent effects and guitars, while Bruno Mars' "Finesse" is more of a 90's/New Jack Swing vibe, two genres that while rooted from the same origins don't necessary jive together.
While the combination of the two works on a technical level, the sum is missing something that each of the individual songs brings to its own respective track. But like it or not, here it is.