  We study double parton scattering (DPS) processes involving electroweak gauge
bosons at the 13 TeV and 100 TeV proton-proton colliders. Specifically, we
focus on three DPS channels: $W$-boson plus two jets ($W\otimes jj$), $Z$-boson
plus two jets ($Z\otimes jj$), and same-sign $W$ pair production ($W^\pm\otimes
W^\pm$). We demonstrate that the $Z\otimes jj$ process, which has not been paid
too much attentions, is the best channel for measuring effective cross section
$\sigma_{\rm eff}$. The accuracy of $\sigma_{\rm eff}$ measurement in the three
DPS channels, especially the $W^\pm\otimes W^\pm$ production, is significantly
improved at the 100 TeV colliders. We advocate that combined analysis of the
three DPS channels could test the universality of effective cross section
$\sigma_{\rm eff}$.
