Tested on Intel Graphics 620 with the latest Windows drivers as of November 8, 2017.
Dual source blending lets you output an additional color from the fragment shader, which can then be used in the blend equation through the "SRC1" factors. Trying to create a graphics pipeline with the following blend modes, like for example:
srcAlphaBlendFactor = VK_BLEND_FACTOR_ONE_MINUS_SRC1_ALPHA;
dstAlphaBlendFactor = VK_BLEND_FACTOR_SRC1_ALPHA
and then outputting to a secondary color in the fragment shader to actually make use of this functionality, crashes in vkCreateGraphicsPipelines with an invalid access to 0x00000008.
Dual source blending support is advertised by the driver and I do enable it, so I'd expect it to work.
