My laptop has 2 graphics card (AMD)

I have recently discovered that my Toshiba SATELLITE L50D-B, has 2 graphics card built in: AMD Radeon R5 M230 Series(1024MB) and AMD Radeon(TM) R5 Graphics(4GB). Im wondering why i have 2 of them and i want to know which one is being used when im playing games? Which is the real or main card of the system?

MY LAPTOP SPECS

*Processor AMD A8-6410 APU with AMD Radeon R5 Graphics Manufacturer AMD Speed 2.0 GHz Number of Cores 4

*Video Card 1 AMD Radeon R5 M230 Series Manufacturer ATI Chipset Radeon R5 M230 Dedicated Memory 1024 MB Total Memory 1024 MB

*Video Card 2 AMD Radeon(TM) R5 Graphics Manufacturer ATI Chipset AMD Radeon(TM) R5 Graphics Dedicated Memory 3.0 GB Total Memory 4.0 GB

*Memory 8.0 GB

*Operating System Microsoft Windows 10 (build 10240), 64-bit Service Pack 0 Size 64 Bit Edition

*Display Maximum Resolution 1366 x 768 DVD MATSHITA DVD-RAM UJ8G2 CD MATSHITA DVD-RAM UJ8G2

*Drive: Size 918.6 GB Free 503.6 GB