Gurobi vs XpressMP, or both?

Is SRL using both Gurobi and XpressMP at the same time? Some of the test files (e.g [1]) define variables to both Gurobi and XpressMP. I wonder if it is necessary. If not, I wonder if it is easy to add the option to declare one of these as the default solver, in the config file (like in case someone does not have access to Gurobi, but XpressMP).

[1] https://gitlab-beta.engr.illinois.edu/cogcomp/illinois-srl/blob/master/tests/srlTester.sh