you first need to decide which variables are dependent, and which ones are independent...
What are your research questions?
If you have 2 independent / 1 dependent variable, then do multiple regression.
If you have 1 independent / 2 dependent variables, then:
- do multivariate regression if it makes sense to combine the 2 dependent variables
- do separate simple regressions if it does not make sense to combine the 2 dependent variables