It would be slightly easier to understand your problem if you showed us the some example code demonstrating the issue as well as the full error that you receive.
What I’m understanding is that there is an Oscar.nrows and Matlab.nrows function, which they both try to export. If you load them via import rather than using, you can avoid the name collision. To refer to either nrows, you could then fully qualify which function you are referring to.
module ModuleWhereYouNeedImportBothOscarAndMatlab
import Oscar
import Matlab
function foo(...)
Oscar.nrows(...)
Matlab.nrows(...)
end
end