R5 340 in Dell 7040 SFF using vga adapter

Equipment: Dell Optiplex SFF  with R5 340 (DVI and DP outs)

2x Dell S2415H monitors


My Dell monitors only have HDMI and VGA connectors.  So, I used a DP to VGA adapter for one monitor (success) and then attached a splitter to the DVI (DVI to DVI and VGA splits) and ran a VGA to the other monitor.  Using the splitter, I can't get an image on the monitor.  I also tried this with just a DVI to VGA adapter without the splitter and was able to duplicate the display, but not extend.  Is this a limitation on the card output?  Driver?  User error?