I have a 3470 HD card in a Windows 10 Home 64-Bit HP Desktop.
When I use the older 8.970.100.9001 driver, the OS detects the dual HP EliteDisplay E201 monitors with no problem and I can extend across.
If I upgrade to the latest 15.7.1 driver, the display works fine, but the OS can't see that I have two monitors attached. All it does it duplicate the screen on both. I'm unable to extend.
Normally, I wouldn't complain about using the older driver, but every so often the driver crashes, I have to boot into safe mode, change to the newer driver, then rollback to the older one.
It's become a giant pain.
The older driver is the only compatible driver for Windows 10 if it was installed via Windows Update. Any other driver probably wouldn't work correctly. It probably would be best to upgrade to a AMD Supported GPU card for Windows 10.
Driver Support for AMD Radeon™ HD 4000, HD 3000, HD 2000 and older Series