I think this has been added in the new K2. Would be awesome to have it works like that.

I felt that it was desirable to make the two pipe types connect to each other. That's how it would work in real life, no?

Perhaps, if there is enough demand, I will make it an option.

Hi, sorry for not updating I have found a mod just for this.
https://mods.factorio.com/mod/no-pipe-touching
so nvm my request

and for the if this is desirable. separating them actually allow for more compact layouts possible.
this has been voted before on K2 discord and it won like 100 to 10 I think.

i specifically sought this mod because i wanted another fluid pipe that didnt connect, i did krastorio and in that steel and iron pipes dont connect, i thought this mod would have the same behavior

Fair call. If I can find time, I will update the mod to have an option to choose between touching / not touching.