DNA is increasingly employed for bio and nanotechnology thanks to its exquisite versatility and designability. Most of its use is limited to linearised and torsionally relaxed DNA but non-trivial architectures and torsionally constrained — or supercoiled — DNA plasmids are largely neglected; this is partly due to the limited understanding of how supercoiling affects the rheology of entangled DNA. To address this open question we perform large scale Molecular Dynamics (MD) simulations of entangled solutions of DNA plasmids modelled as twistable chains. We discover that, contrarily to what generally assumed in the literature, larger supercoiling increases the average size of plasmids in the entangled regime. At the same time, we discover that this is accompanied by an unexpected increase of diffusivity. We explain our findings as due to a decrease in inter-plasmids threadings and entanglement