Fixed duplicated dimension issue on DFColumns interface
Fixed duplicated dimension issue on DFColumns interface

vascotenner/holoviews,basnijholt/holoviews,basnijholt/holoviews,ioam/holoviews,basnijholt/holoviews,ioam/holoviews,ioam/holoviews,vascotenner/holoviews,vascotenner/holoviews