[2.1.9] Belt dragging underground creation edge case deletes a belt

[cosycat]

If I drag along in the Screenshot below, it will create the underground belts as expected, going underneath the whole construct, but it will delete the rightmost belt.
Expected behavior would be that it does not delete any belt.

Start

Screenshot 2026-07-07 at 18.19.53.png (9.1 MiB) Viewed 74 times

After Dragging

After dragging.png (1.73 MiB) Viewed 74 times

[Loewchen]

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