I've noticed a peculiar phenomenon when upgrading items. Upgrading with robots works fine, but when using Autobuild, it upgrades incorrectly. Through testing, I've found that this issue only occurs when normal pipes are connected to Advanced Fluid Handling pipes.
I've attached a video to demonstrate this. The first part shows robot upgrading, which works correctly. The second part demonstrates Autobuild upgrading, where an extra pipe appears.

https://drive.google.com/file/d/1O9UwyEnUCRz5f6g4ev6EaIBS9L_RSeTC/view?usp=sharing

Looks very weird. No clue, whats happening at glance. Need to reproduce myself and go through the code.
Thanks for the report.

OK, I think I found the problem. And I fixed it.
UG-Pipes no longer get upgraded in pairs, but that shouldn't be problem? Actually, it probably never worked or only in special cases

If its a problem, I need to find a better solution to find the correct pair neighbor to upgrade