Steps to reproduce the issue:
1. Open attached project ("Test1").
2. Open scene named "main".
3. Enter the Play mode.

Actual result:
Graphics.BlitMultiTap dos not work when it is given array as a parameter.

Expected result:
Graphics.BlitMultiTap should work when it is given array as a parameter.

4. Open script named "Graphics_BlitMultiTap".
5. Navigate to the method "OnRenderImage()" and temporary delete this line of code: Graphics.BlitMultiTap(source, destination, mat, offsets);
6. Add this line of code and save the script: Graphics.BlitMultiTap(source, destination, mat, Random.insideUnitCircle * 16, Random.insideUnitCircle * 32);
7. Enter the play mode and notice that Graphics.BlitMultiTap works fine if it is given vector2's one by one manually.

Reproduced with:
5.1.5f1, 5.2.5f1, 5.3.6p2, 5.4.0f3, 5.5.0a5.

Note1:
More information could be found here: http://forum.unity3d.com/threads/graphics-blitmultitap-only-taps-once-unity-5-2-dx-11.355795/
https://docs.unity3d.com/ScriptReference/Graphics.BlitMultiTap.html

Note2:
GIFs attached.