[2.0.10] Hand-placing UG belts over blueprinted UGs replaces both ends, unless same tier as BP

[Ch4rl1e]

Rough title, sorry.

This seems to be related to the QoL feature that replaces both ends of 2 connected undergrounds when hand build a different type of underground (e.g. red placed over yellow).

This feature seems to take take charge even when building over a blueprinted underground, placing real tiles on both ends with 1 left-click (assuming you have the items available in your inventory), but only so long as the blueprinted underground is of a different type. Consequently, this weird disparity is created where it's easier to place undergrounds in a blueprint if they're of a different type/tier to what is being built.

Test set up:

10-24-2024, 19-36-35.png (495.68 KiB) Viewed 218 times

Placing red UGs on each:

factorio_f3st4S3M70.gif (12.74 MiB) Viewed 218 times

I would expect it to be consistent and either

1. place both ends regardless of blueprint tier, or,
2. (less preferable) to not place both ends at all whilst placing over blueprints.

Possibly - but unlikely to be - relevant: This was noticed and tested on a multiplayer server.

[Loewchen]

94307

[erronius]

Wow, amazing reproduction. I've also found this behavior strange. I just want to add as a note that this was case pre-2.0/Space Age.