Tested with VDub2 (x86 & x64) 43943 and avs 3.40.
This works :
Code:
a0=colorbars(width=1920,height=1080,pixel_type="yv12").trim(0,9).ConvertBits(16).ConverttoYUV444()
a1=a0
StackVertical(a0,a1)
ConvertBits(8)
this doesn't :
Code:
a0=colorbars(width=1920,height=1080,pixel_type="yv12").trim(0,9).ConvertBits(16).ConverttoYUV444()
a1=a0
StackVertical(a0,a1)
#ConvertBits(8)