Reproduce the steps:
1. Create the setup shown below
2. Test as labeled in the figure below.
3. After pulling the signal source marked RANDOM in the figure below, the piston will extend at random.
The expected behavior is that after pulling the signal source marked RANDOM in the figure below, the piston that always extends is the left piston.

Note that the redstone torch itself does seem like it is setting a "front" direction when powering a redstone dust above it, but it doesn't when the dust is below.