Yes, you certainly can! The only thing you have to take into account is that you might end up in a higher tax bracket. This is because the Tax Authorities (Belastingdienst) add both gross incomes together when you do your income tax (inkomstenbelasting). It is therefore possible that part of your income will be taxed in a higher tax bracket. If you want to know exactly which bracket you fall into, check the website of the Tax Authorities