The syntax for Map-side join and Reduce-side join are different. So, there would not be conflicts running the join.
The example for Map-side join is:
SELECT /*+ MAPJOIN(dataset2) */ dataset1.name, dataset1.eid,dataset2.eid FROM dataset1 JOIN dataset2 ON dataset1.first_name = dataset2.first_name;
The exmaple for Reduce-side join is:
select emp.name, dept.deptname from emp join dept on emp.deptid=dept.deptid;