Assigning mutiple profiles to the same user

I would like to assign 2x profiles to the same user using JIT rules, each rule appears to only allow provisioning 1 profile and if applying mutiple rules to the same user the last rule that applies seems to overwrite the previous assignment. is there a way to make the profile assignments additive?

Thanks

Start by reproducing the issue with two JIT rules assigning profiles to one user, then trace the current rule evaluation and profile-assignment entry points. Done means matching rules retain both profile assignments instead of the last applicable rule overwriting the earlier one.

Written by the indexing model from the issue text.