Render pipeline output merge order

I am trying to draw two triangles in a single drawcall. The two triangles are parallel. And the forward direction of camera is along the normal of those triangles which is perpendicular to both triangles. From camera view, the two triangles are perfectly overlapped.

Alpha blend is enabled with blendop being srcAlpha and invSrcAlpha. The color of triangle in back is (0, 1, 0, 0.5), the color of triangle in front is (1, 0, 0, 0.5). And the RT is cleared as black. The pixel shader simply output the triangle color.

Here is an image to show the scene, the vertices of triangles are indexed as in the image.

What could be the final color in RT, could be all (0.5, 0.25, 0). In graphics pipeline, is it guaranteed the pixel of green triangle output before red triangle?

It looks like DirectX pipeline guarantees the order.

"DirectX rendering follows a strict set of rule that ensure triangles are always rendered in the order they are submitted: if two triangles are overlapping on the screen, the hardware guarantees that Triangle 1 will have its color result blended to the screen before Triangle 2 is processed and blended."

Here is the link https://software.intel.com/en-us/gamedev/articles/rasterizer-order-views-101-a-primer, and at the section "DirectX Pipeline and the limitations of UAVs".