Thanks for the clarification haha, I didn't expect people to actually reply to my screenshot after such a long time! But always happy to see you guys in the comments!

Doesn't actually depend on colours I don't think. From my testing it appears to be when two Excursion Funnels of the same direction overlap. In most but not all cases this is usually done with an orange and blue funnel that are put together anyway.

HOLLOW PURPLE! (this happens because blue + any shade of red = purple... [or pink depending on what shade of red or blue]

oooh.. thats bloody make sense