A study of data of candidates contesting General Elections 2018 shows that of all dual nationality holder candidates majority of them have British nationality i.e., 41.
The data was provided to the Election Commission of Pakistan (ECP) by the Federal Investigation Agency which used travel data on Integrated Border Management System (IBMS) to find out the dual national candidates. The FIA had identified 118 cases. However, since some candidates had filed nomination papers both for national and provincial assemblies and some of them were withdrawn by the FIA later on, our analysis reveals of them 87 individuals have dual nationalities. The following map shows country wise nationalities of these candidates.
You can see details of all the candidates here.