I know what you mean. I would prefer not to have replicated CSS, but in practice, on large projects I find myself working on one element at a time, across all platforms. So it's helpful to have the style for one element grouped together and saves scrolling up and down or flipping between different scss files. In the end the css is compacted anyway so I try not to worry about any excess replication as long as it's clean and clear in the SCSS.
It really should be a feature of SASS compiling (to group the queries) as is discussed here https://github.com/nex3/sass/issues/116