Two Mathematics grades at GCSE, can I use both on UCAS

Basically my teacher made us sit a modular exam (AQA) and linear (Edexcel) in order to have more chance of obtaining that crucial Maths grade, but I don't know whether I can use both on UCAS or whether I can only use one (suppose it's like having two geography GCSE's with different exam boards). I don't really care tbh just wanting to know seens as you need to declare all your grades!

Thanks